Gas useage

[melonfool]

I read the link.
I always thought putting a boiler in the loft (or an uninsulated garage) was a bad idea, something just didnt ring right to me. All of the reasons are pretty obvious once they've been pointed out.

I'll definitely move it if I replace it, it's right above my head and I hate that!

Mel

[melonfool]

Hi

Thank you - I am aware of this issue, but I'm not sure there is much I can do about it. The leak cannot be found. It's been going on for years, so I assume there is no inhibitor at all now! Can this be replaced?

Mel

Yes - you are supposed to replace it every year!.

We have a slow leak - might have been there on the gravity fed system as well but we only discovered it when we went pressurised!. Takes about 3 or 4 seconds to top up every couple of months, which as we get 6L/min at the tap into an open jug, and the heating system is pressurised, probably equates to about 250ml pr time of a couple of litres per year. We have rough equivalent of 20 singe rads 1200x600 so about 70L in the system. The installer left me a bottle (the system takes 2) and said to add it after 6 months, so that's only a few weeks away.

Paul

Well, in 25 years of home ownership and boiler ownership no-one has ever mentioned this to me and no plumber has ever tried to sell me this service. Odd!

I'll look into this.

(mine needs topping up weekly when the heating is on)

Mel

[melonfool]

Hello again, MelonFool,

Sorry I can't help you with the gas issue. But I know a little bit about plumbing, and I did notice your point about your water leak.

If this was happening to me, what would worry me is (we run an open vented system, you mentioned "repressurised" so I guess that yours is combi, or a sealed non-combi system, but I believe that the principle is the same) was that when a CH loses fluid, it's not just water that is leaking its a mixture of water+CH inhibitor. So when the mains system tops up the "water" to the required level, your resulting fluid contains less and less inhibitor. Hence the system will rust internally - eventually destroying the boiler.

Apologies if someone in one of the intervening posts has already pointed this out to you. Sorting out a CH leak, isn't necessarily the end of the world, there could be several approaches to take, but paying out for a new boiler when you've got unresolved pipe work would be bad I think.

Matt

Hi

Thank you - I am aware of this issue, but I'm not sure there is much I can do about it. The leak cannot be found. It's been going on for years, so I assume there is no inhibitor at all now! Can this be replaced?

Yes. With open-vented systems just go to your water expansion (header) tank, either string up the ballcock, or switch off your water feed. Then remove an equivalent of water from the tank (just scoop it with a jug!) and bung in your CH inhibitor (I usually get Fernox). Then switch the water feed back on.

Sometimes (to get a better/quicker) distribution of the inhibitor you can remove more water, by opening a drain cock e.g. near the boiler or a rad, and 1) take out enough to empty the header tank, then another gallon or so.

I've no experience of a pressurised system, I thiink that you inject it in.

The boiler itself isn't that expensive to be honest. Not as expensive as digging up a floor to find a leak that you may still not find!

Thing is, I don't see the point of trying to optimise your gas usage, if your boiler is already compromised by an absolute shedload of rust particles.

Couple of options for you to consider.

1. Obviously since the leak is in your CH system, it will be from a pipe feeding a rad.
2. Figure out how your rads are fed. 20 years ago I tee-ed of the pipe to an existing rad in order to plumb one in an extension, by just feeling (for the warmth) along at the bottom of the skirting board in between the boiler and the first rad in the circuit! (First rad is usually the first to warm up). Then I just pulled up the carpet, scraped up some screed and located the feed pipe.
3. Of course some rads are fed by running the pipes to the rad down the wall. Then theres a loop in the ceiling / loft space etc..

A classic CH leak, I find is that some bright spark has done a "exposed timber" job and stripped their floorboards. And they (in order not to sh@g the sander they ve just hired) tap the floorboard nails under the wood surface. Only to hit a hidden pipe! Did the last occupant do anything like this or change something near where pipes could go.

It all really depends on how much effort and thinking you are prepared to do. (But perhaps you need to see whether you can hire someone like this https://www.leakdetectionspecialists.co ... -detection). I mean it aint rocket science, must be electrical/induction based ways of figuring out theres a water pipe nearby etc.

Another option is don't try to find the leak, just cap off the existing feed and return pipes and re-pipe your rads with good copper (or plastic in hidden spaces). You either hide pipes below skirting, or clip them just above.

Not wanting to upset you, but I think youre crazy trying to reduce your gas bill, but with a fundamental CH system issue.

Matt

No header tank.

The system has been looked at by two plumbers, with a few things tightened up and a couple of valves replaced just in case.

It cannot be upstairs because any leak would, after three years of this, be coming through the ceiling, surely? So, I deduce it is on the ground floor.

In 2019, I had two radiators replaced (one I wanted made into a double shorter one so I could put some furniture against the wall where it was, and the other was long and low, but single, so I had that replaced by the same size but double to add back some of the loss from the replaced one). Soon after, as in - part of the same works - I had new wooden flooring. The wooden flooring does not involve nails. The floor underneath is concrete and I think the pipes are along the edges of the concrete floor.

I had back the plumber who installed the rads, he said they were fine, then told me to speak to the boiler manufacturer. (Rude - yes!)

There are two other rads downstairs, one is very small in the loo and one is bigger, in the kitchen. These two are easy to check, pipes run along the skirting or are boxed in, neither are showing any signs of a leak.

Thus, I conclude it must be the rads in the living room, and under the wooden flooring, going into the concrete. Not as a simple as 'pulling back a bit of carpet' I'm afraid. The wooden flooring is not showing any signs of water damage/buckling etc.

I would like to get it solved but have concluded so far that there's not much can be done short of digging up the very expensive engineered wood flooring - I can buy a LOT of gas before I break even on the cost of doing that! I do have a plan to replace the downstairs loo rad at some point so I might expedite that, just in case it helps - only because it's a bit old and rusty looking.

I will call one of those tracing guys, I didn't know they existed. Thank you.

It has been confirmed up thread (quite far) that the leak will not be causing me to use more gas though.

Mel

[melonfool]

Thing is, I don't see the point of trying to optimise your gas usage, if your boiler is already compromised by an absolute shedload of rust particles.

Matt

Because the object is to make the most of what you have. How do you know the boiler is full of rust?

MrsF's car does 30 mpg on a run if we're careful, but half that when taunted. Doesn't mean we should always try and get it down to 15mpg

Paul

I very much doubt my boiler is full of rust, it's 5 years old and runs fine, it's been serviced twice in the five years I have lived here and this has not been mentioned. Must book a new service.

The system may be full of rust though which I think it was MCB meant?

Mel

[TheMotorcycleBoy]

Thing is, I don't see the point of trying to optimise your gas usage, if your boiler is already compromised by an absolute shedload of rust particles.

Matt

Because the object is to make the most of what you have. How do you know the boiler is full of rust?

MrsF's car does 30 mpg on a run if we're careful, but half that when taunted. Doesn't mean we should always try and get it down to 15mpg

Paul

I very much doubt my boiler is full of rust, it's 5 years old and runs fine, it's been serviced twice in the five years I have lived here and this has not been mentioned. Must book a new service.

The system may be full of rust though which I think it was MCB meant?

Mel

Yes. That's certainly been my experience, though that's restricted to open-vented systems. About 8 years we ransacked some bits of our heating infrastructure, including asbestos/concrete hot and colder headers. They weighed a ton, me, Mel and our plumber taking them down from a 6ft high platform in the loft (note our house is a nightmare).

We also replaced the boiler and the cylinder. The existing system had been neglected badly. Whilst I do expect, colloidal iron oxide (it looks like jelly and innocently loiters in the header), even in a decent open system, what I also found was 1000s of hard iron oxide sediment in the header ! This had obv flaked off from rad internal surface etc. Boiler must have been pretty clogged. (Bit like a heavy smoker I guess!).

We flushed out the old system and now I'm vigilent with the fernox. We also have a magnetic iron particle inline. Fortunately in it's annual inspection, this is now very clean.

So it is possible that the heat exchanger in your boiler could be suffering. I really wouldn't know. But what I do know is that you can apparently buy test kits to determine the state of your CH system water. All I can really say, Mel, is that the leak could well be an issue. But of course since it's not my system I don't know exactly how bad yours has got. I also that zero experience of closed pressurised system, but presumably their mains feed will still be oxygenated mains water, so each time the lost water is replaced, more O2 comes into potentially rust out your rads.

Matt

[modellingman]

Thing is, I don't see the point of trying to optimise your gas usage, if your boiler is already compromised by an absolute shedload of rust particles.

Matt

Because the object is to make the most of what you have. How do you know the boiler is full of rust?

MrsF's car does 30 mpg on a run if we're careful, but half that when taunted. Doesn't mean we should always try and get it down to 15mpg

Paul

I very much doubt my boiler is full of rust, it's 5 years old and runs fine, it's been serviced twice in the five years I have lived here and this has not been mentioned. Must book a new service.

The system may be full of rust though which I think it was MCB meant?

Mel

https://www.screwfix.com/p/adey-cp1-03- ... 22mm/49961

Do you have one of these (or something similar) fitted to your system? These tend to get fitted when installing a new boiler (I suspect that it will be a condition of the guarantee offered by the manufacturer). The have isolation valves fitted allowing the unit to be drained of accumulated crud and the appropriate chemical treatments to be added.

[staffordian]

Regarding the water leak, I wonder if it's possible that the leak is within the boiler, rather than the pipework? Possibly pinholes in the heat exchanger?

I might be talking complete rubbish, but seem to recall this can happen. I wonder if Mike4 can comment.

[TheMotorcycleBoy]

Hi

Thank you - I am aware of this issue, but I'm not sure there is much I can do about it. The leak cannot be found. It's been going on for years, so I assume there is no inhibitor at all now! Can this be replaced?

Mel

Yes - you are supposed to replace it every year!.

We have a slow leak - might have been there on the gravity fed system as well but we only discovered it when we went pressurised!. Takes about 3 or 4 seconds to top up every couple of months, which as we get 6L/min at the tap into an open jug, and the heating system is pressurised, probably equates to about 250ml pr time of a couple of litres per year. We have rough equivalent of 20 singe rads 1200x600 so about 70L in the system. The installer left me a bottle (the system takes 2) and said to add it after 6 months, so that's only a few weeks away.

Paul

TBH On a healthy open vented system, I don't think you should need to replace the inhibitor annually. I guess testing it reasonably often isn't a bad move, however.

Now that our system is good, every couple years I'll take off a litre from the top of our header and bung another bottle of fernox in.

But on two of the three O/V systems I've had to "live with", a full drain and replenishment of the system can take between 6-12 months to blow out the last residual trapped air bubbles[1]. So I try to disturb ours as little as possible!

Matt

[1] Hint. Turn the circ pump up to max to help bleed out the bubbles on an open vented.

[TheMotorcycleBoy]

Hi

Thank you - I am aware of this issue, but I'm not sure there is much I can do about it. The leak cannot be found. It's been going on for years, so I assume there is no inhibitor at all now! Can this be replaced?

Mel

Yes - you are supposed to replace it every year!.

We have a slow leak - might have been there on the gravity fed system as well but we only discovered it when we went pressurised!. Takes about 3 or 4 seconds to top up every couple of months, which as we get 6L/min at the tap into an open jug, and the heating system is pressurised, probably equates to about 250ml pr time of a couple of litres per year. We have rough equivalent of 20 singe rads 1200x600 so about 70L in the system. The installer left me a bottle (the system takes 2) and said to add it after 6 months, so that's only a few weeks away.

Paul

Well, in 25 years of home ownership and boiler ownership no-one has ever mentioned this to me and no plumber has ever tried to sell me this service. Odd!

I'll look into this.

(mine needs topping up weekly when the heating is on)

Mel

It's pretty dull affair TBH Mel, and many plumbers would rather relieve you of a few 1000 to replace a boiler, and sell you a (rip-off) "power flush" to repair the damage, than an hour or so work, topping up a bit of inhibitor.

A few decades when I discovered how difficult it was to get any "tradesman" [1] but in particular plumbers to actually do anything useful for me, I decided it was time to teach myself these things.

Matt

[1] Apologies to all decent tradesmen who may be on this site. I have meet a few decent ones. But the good ones are quickly discovered and inundated by their clientele, in my experience.

[Itsallaguess]

Mine needs topping up weekly when the heating is on

If you're losing pressure mostly when the heating is on, and there's no other obvious signs of water damage in the house, then I'd be very tempted to keep an eye on the external pressure-release valve pipe that'll be popping out of an outside wall somewhere, often with just a little 90-degree stub of open pipe on it...

If there's ever been a reason for that pressure-release valve to activate in the past, then they quite often have issues with being re-seated into a completely closed position afterwards, and can sometimes have a tendency to continue to 'leak' over time.

One quick and cheap way to check this is to use an elastic band to lightly put a clear plastic bag such as a freezer bag, over the end of the outside pressure-release pipe, and just keep an eye on it when you've turned on the heating. If you see it filling with water over a period of days, or (worse!) if the bag has quickly dropped off due to having been too-swiftly filled with leaking system-water, then you've at least found out where the water's going, even if you might not quite know why at that particular stage...

If that happens, another alternative reason might be related to a flat boiler expansion vessel, but if you've had a couple of plumbers round to take a look in the past, then I'd have expected them to consider that option early on in any potential diagnosis, and for them to check it, so that's less likely than a slightly leaking pressure-release valve, but given that both potential issues, if either are occurring, are likely to result in water coming out of that external over-pressure pipe, then using the banded plastic-bag trick to potentially diagnose this feels like a potential DIY check, so long as safe access to that external pipe is available to you...

Cheers,

Itsallaguess

[DrFfybes]

Mine needs topping up weekly when the heating is on

If you're losing pressure mostly when the heating is on, and there's no other obvious signs of water damage in the house, then I'd be very tempted to keep an eye on the external pressure-release valve pipe that'll be popping out of an outside wall somewhere, often with just a little 90-degree stub of open pipe on it...

That was exactly the thought that popped into my head when I saw it. Does it ONLY lose pressure when the heating is running?

If there's ever been a reason for that pressure-release valve to activate in the past, then they quite often have issues with being re-seated into a completely closed position afterwards, and can sometimes have a tendency to continue to 'leak' over time.

One quick and cheap way to check this is to use an elastic band to lightly put a clear plastic bag such as a freezer bag, over the end of the outside pressure-release pipe, and just keep an eye on it when you've turned on the heating.

ISTR her boiler is in the loft - might not be easy to do that Our previous house boiler was in the garage on the internal wall to the lounge and the PRV went into the same pipework as the coolant drain. although the new one is separate.

If that happens, another alternative reason might be related to a flat boiler expansion vessel, but if you've had a couple of plumbers round to take a look in the past, then I'd have expected them to consider that option early on in any potential diagnosis, and for them to check it, so that's less likely than a slightly leaking pressure-release valve, but given that both potential issues, if either are occurring, are likely to result in water coming out of that external over-pressure pipe,

Good point. When we had this problem it was a faulty expansion vessel.

Mel - you said you have an accessible pressure indicator. One thing to try is keep a log of the pressure before and after heating has been on (although I guess it isn't on at the moment?). If the pressure holds static for a few days it should climb when the boiler is run and drop back to the same level after. If it drops lower then at least you can tie it in to the boiler needing to be in use to find the problem. If it is a system boiler with a hot water tank then you can look before/during/after the hot water is on, but obviously this won't work with a combi.

Paul

[Itsallaguess]

If there's ever been a reason for that pressure-release valve to activate in the past, then they quite often have issues with being re-seated into a completely closed position afterwards, and can sometimes have a tendency to continue to 'leak' over time.

One quick and cheap way to check this is to use an elastic band to lightly put a clear plastic bag such as a freezer bag, over the end of the outside pressure-release pipe, and just keep an eye on it when you've turned on the heating.

ISTR her boiler is in the loft - might not be easy to do that

Hopefully Mike's added 'Poor access to outside pressure-release pipework' to his list of loft-siting disadvantages...

More seriously though, sometimes these external pipework discharges can be fairly easily determined by a dark stain on the outside brickwork or pebble-dashing, indicating there's been dirty system-water being expelled from the outside open end, and that's especially so if there's regular top-up-then-expel processes going on over a long and cold winter...

Either way, it's just something I wanted to highlight given Mel's original 'topping up all the time in the winter' statement, as it begins to potentially highlight that the system might only be losing water when being overly pressurised during system-heating cycles, which sometimes at least helps with some diagnosis pathways if that turns out to be true...

Cheers,

Itsallaguess

[melonfool]

https://www.screwfix.com/p/adey-cp1-03- ... 22mm/49961

Do you have one of these (or something similar) fitted to your system? These tend to get fitted when installing a new boiler (I suspect that it will be a condition of the guarantee offered by the manufacturer). The have isolation valves fitted allowing the unit to be drained of accumulated crud and the appropriate chemical treatments to be added.

Not that I can see - where would it be?

The boiler was new March 2017, the house went on the market....March 2017.....I moved in Aug 2017. I suspect there was an issue with the old boiler that they had learned to live with but knew would be an issue on selling, so they fitted the smallest cheapest boiler they could get away with. It had a one year warranty, it was that cheap! They had no thermostat, which was bewildering to me. I asked them how they controlled the heating and they said they just turned it on or off (I did wonder if they had a Nest or something and just took it with them). I had a therm fitted pretty quickly by csearle, which is the therm that failed earlier this year and had to be replaced at great cost and which I now can't work!

Mel

[melonfool]

Regarding the water leak, I wonder if it's possible that the leak is within the boiler, rather than the pipework? Possibly pinholes in the heat exchanger?

I might be talking complete rubbish, but seem to recall this can happen. I wonder if Mike4 can comment.

As far as I know, this is possible, but the boiler has been checked twice now, and serviced, since this started. Plus if it was leaking, wouldn't there be some water somewhere - under it, leaking through the ceiling onto my head when I'm in bed?

Mel

[melonfool]

Mine needs topping up weekly when the heating is on

If you're losing pressure mostly when the heating is on, and there's no other obvious signs of water damage in the house, then I'd be very tempted to keep an eye on the external pressure-release valve pipe that'll be popping out of an outside wall somewhere, often with just a little 90-degree stub of open pipe on it...

If there's ever been a reason for that pressure-release valve to activate in the past, then they quite often have issues with being re-seated into a completely closed position afterwards, and can sometimes have a tendency to continue to 'leak' over time.

One quick and cheap way to check this is to use an elastic band to lightly put a clear plastic bag such as a freezer bag, over the end of the outside pressure-release pipe, and just keep an eye on it when you've turned on the heating. If you see it filling with water over a period of days, or (worse!) if the bag has quickly dropped off due to having been too-swiftly filled with leaking system-water, then you've at least found out where the water's going, even if you might not quite know why at that particular stage...

If that happens, another alternative reason might be related to a flat boiler expansion vessel, but if you've had a couple of plumbers round to take a look in the past, then I'd have expected them to consider that option early on in any potential diagnosis, and for them to check it, so that's less likely than a slightly leaking pressure-release valve, but given that both potential issues, if either are occurring, are likely to result in water coming out of that external over-pressure pipe, then using the banded plastic-bag trick to potentially diagnose this feels like a potential DIY check, so long as safe access to that external pipe is available to you...

Cheers,

Itsallaguess

That has all been checked and the (not faulty at all!) expansion vessel has been replaced.

The external pipe thing annoyingly goes over next door's garden and is round the side of my house and quite hard to see, but the plumber got their permission and went in with a ladder and took a good look at it - no signs of water, no damage around it, there are no drip signs down the wall and no signs under the pipe on the floor either.

Mel

[melonfool]

Mine needs topping up weekly when the heating is on

If you're losing pressure mostly when the heating is on, and there's no other obvious signs of water damage in the house, then I'd be very tempted to keep an eye on the external pressure-release valve pipe that'll be popping out of an outside wall somewhere, often with just a little 90-degree stub of open pipe on it...

That was exactly the thought that popped into my head when I saw it. Does it ONLY lose pressure when the heating is running?

If there's ever been a reason for that pressure-release valve to activate in the past, then they quite often have issues with being re-seated into a completely closed position afterwards, and can sometimes have a tendency to continue to 'leak' over time.

One quick and cheap way to check this is to use an elastic band to lightly put a clear plastic bag such as a freezer bag, over the end of the outside pressure-release pipe, and just keep an eye on it when you've turned on the heating.

ISTR her boiler is in the loft - might not be easy to do that Our previous house boiler was in the garage on the internal wall to the lounge and the PRV went into the same pipework as the coolant drain. although the new one is separate.

If that happens, another alternative reason might be related to a flat boiler expansion vessel, but if you've had a couple of plumbers round to take a look in the past, then I'd have expected them to consider that option early on in any potential diagnosis, and for them to check it, so that's less likely than a slightly leaking pressure-release valve, but given that both potential issues, if either are occurring, are likely to result in water coming out of that external over-pressure pipe,

Good point. When we had this problem it was a faulty expansion vessel.

Mel - you said you have an accessible pressure indicator. One thing to try is keep a log of the pressure before and after heating has been on (although I guess it isn't on at the moment?). If the pressure holds static for a few days it should climb when the boiler is run and drop back to the same level after. If it drops lower then at least you can tie it in to the boiler needing to be in use to find the problem. If it is a system boiler with a hot water tank then you can look before/during/after the hot water is on, but obviously this won't work with a combi.

Paul

It generally needs topping up every week but has not done since around May. Now - we have an excellent example of 'correlation is not causation' - as that happens to be the same time the bills appear to have dropped which is why I wondered if the bills are more because of the pressure drop and that therefore the pressure drop causes more gas to be used....

But NO! I think we have all agreed that the gas use dropping is normal for the time of year and it is my data recording that is faulty as the gaps are not consistent.

Anyway....boiler is in the loft but the little pipe thing is on an outside wall - although I am in a terraced house the house are slightly staggered so that end of the loft is not attached to anything and has a side wall out of which the pipe pokes - but is over next door's garden.

I will do the experiment with the pressure if I ever turn the heating on, it's not been on at all yet, since May (since three prime ministers ago...). There's no tank. Mind you, the gauge is very small, it's hard to see much between just 1 and 2.

Mel

[staffordian]

Regarding the water leak, I wonder if it's possible that the leak is within the boiler, rather than the pipework? Possibly pinholes in the heat exchanger?

I might be talking complete rubbish, but seem to recall this can happen. I wonder if Mike4 can comment.

As far as I know, this is possible, but the boiler has been checked twice now, and serviced, since this started. Plus if it was leaking, wouldn't there be some water somewhere - under it, leaking through the ceiling onto my head when I'm in bed?

Mel

Probably ok then if the boiler has been checked, but regarding seeing the leaking water, I have a hunch that if the heat exchanger leaks, the escaping water might run out through the condensate pipe, but again, I might be talking rubbish

[Mike4]

Regarding the water leak, I wonder if it's possible that the leak is within the boiler, rather than the pipework? Possibly pinholes in the heat exchanger?

I might be talking complete rubbish, but seem to recall this can happen. I wonder if Mike4 can comment.

As far as I know, this is possible, but the boiler has been checked twice now, and serviced, since this started. Plus if it was leaking, wouldn't there be some water somewhere - under it, leaking through the ceiling onto my head when I'm in bed?

Mel

Probably ok then if the boiler has been checked, but regarding seeing the leaking water, I have a hunch that if the heat exchanger leaks, the escaping water might run out through the condensate pipe, but again, I might be talking rubbish

Nope, you're not talking rubbish. It's a known problem with modern condensing boilers. The heat exchanger cracks and the water that leaks out gets caught and handled by the condensate drainage system so the user never gets to realise that's where the leak is from. They just see the dropping pressure.

What exactly did the people who "checked" the heat exchanger, actually do to check it I wonder. This particular fault is not an easy thing to diagnose...

[modellingman]

https://www.screwfix.com/p/adey-cp1-03- ... 22mm/49961

Do you have one of these (or something similar) fitted to your system? These tend to get fitted when installing a new boiler (I suspect that it will be a condition of the guarantee offered by the manufacturer). The have isolation valves fitted allowing the unit to be drained of accumulated crud and the appropriate chemical treatments to be added.

Not that I can see - where would it be?

The boiler was new March 2017, the house went on the market....March 2017.....I moved in Aug 2017. I suspect there was an issue with the old boiler that they had learned to live with but knew would be an issue on selling, so they fitted the smallest cheapest boiler they could get away with. It had a one year warranty, it was that cheap!

They are usually fitted on the central heating circuit close to the boiler itself. The screwfix page I linked to shows a common installation position in one of the enlarge able photographs.

The reason for asking was that these filters are intended to prevent the type of corrosion problems that can occur in central heating systems, both in radiators and in the boiler itself.

modellingman

[DrFfybes]

Nope, you're not talking rubbish. It's a known problem with modern condensing boilers. The heat exchanger cracks and the water that leaks out gets caught and handled by the condensate drainage system so the user never gets to realise that's where the leak is from. They just see the dropping pressure.

What exactly did the people who "checked" the heat exchanger, actually do to check it I wonder. This particular fault is not an easy thing to diagnose...

Mike is starting to sound like he's only 4 posts away from getting his loft climbing gear out and popping round as it will be quicker than remote diagnosis