Central Heating leak.

[Parky]

I have a small leak on a plastic push fitting behind a radiator. It doesn't leak when the heating is on, but leaks about a cupful of water overnight, presumably as the system cools and the faulty rubber seal hardens (?). The pressure in the system is falling, but very slowly. I have looked at adding leak sealing compound to the system, but most reviews say it often doesn't work well, and is not a permanent solution, so I am faced with draining the system and removing the radiator. No problem, but other than installing a new fitting, and adding a shot of corrosion inhibitor when I refill the system, is there anything else I should be doing, or looking for when I do the job? I suspect the system has not been touched for 10 years since new (we moved in 3 years ago). Any tricks to help with the job?
Thanks in advance.

[pochisoldi]

I have a small leak on a plastic push fitting behind a radiator. It doesn't leak when the heating is on, but leaks about a cupful of water overnight, presumably as the system cools and the faulty rubber seal hardens (?). The pressure in the system is falling, but very slowly. I have looked at adding leak sealing compound to the system, but most reviews say it often doesn't work well, and is not a permanent solution, so I am faced with draining the system and removing the radiator. No problem, but other than installing a new fitting, and adding a shot of corrosion inhibitor when I refill the system, is there anything else I should be doing, or looking for when I do the job? I suspect the system has not been touched for 10 years since new (we moved in 3 years ago). Any tricks to help with the job?
Thanks in advance.

1. Use a pipe freezing kit (assuming there's a accessible pipe run) together with turning off the radiator valves to allow you to replace the duff connector. (Note that water+inhibitor will be harder to freeze compared to plain water)
2. Look at the whole system and look for jobs that would required a draindown (e.g. fitting thermostatic radiator valves), then do a draindown.
3. Consider getting someone in to do the job - get a quote to do the job, then work out how long it would take you to do the job.
Subtract the cost of tools from the quote, and then divide the figure by the number of hours required, and then ask yourself "Am I paying myself enough to do this task?", and "Is it worth getting my hands dirty for £X/hr?"

PochiSoldi

[DrFfybes]

If using a freezing kit be aware that it can take a while longer to freeze as the plastic pipes insulate better than copper.

Freeze well back from the area you are working on, as you can flex the plastic pipe whilst making the repair and 'crack' the ice plug.

Lastly work out exactly how you are going to repair the leak before you start - are you going to try and dissemble the joint and replace the seal, replace the union.

Of course if you can't get to it because of the radiator, then you have no choice other than to drain down. I just removed and replaced a rad for decorating, and didn't top up the inhibitor as I reckoned it was under 10% of the system volume.

If you have TRVs then try and find the closure cap rather than just turning it down to min, otherwise at this time of year you might find the house gets very cold overnight and the TRV opens again.

Paul

[stewamax]

If you have TRVs then try and find the closure cap rather than just turning it down to min, otherwise at this time of year you might find the house gets very cold overnight and the TRV opens again.

I'll second that. I made the same mistake many years ago one cold winter overnight. I came down the next morning to a brand new swimming pool in what was the drawing room. If you haven't got a closure cap, a 5p piece between the head and the pin (sticking up from the body) may suffice.

[DrFfybes]

If you have TRVs then try and find the closure cap rather than just turning it down to min, otherwise at this time of year you might find the house gets very cold overnight and the TRV opens again.

I'll second that. I made the same mistake many years ago one cold winter overnight. I came down the next morning to a brand new swimming pool in what was the drawing room. If you haven't got a closure cap, a 5p piece between the head and the pin (sticking up from the body) may suffice.

I was fortunate that the TRV leaked slightly so I had a bowl under it and some kitchen roll to "wick" the water into the bowl so ended up with a bowl of liquid.

I've since made blanking caps that screw on to where the radiator tails fit to the valves.

Paul

[Howard]

I had a leaking thermostatic valve in a downstairs room replaced last week by a professional (this was covered by my service plan - £13 a month).

The plumber said it was not good practice to use a freezing kit. He part-drained the system (five bed house around 20 rads - took about 20 minutes) and this meant that there was very little leakage. System was refilled and Fernox F1 added. This took another 20 minutes.

Only negative is that it has taken several days for the air to escape from the (non pressurised, gravity) system. I know the key radiators to bleed so it hasn't been that much of a problem.

I live in an expensive area for plumbers, but guess it would cost around £100 or less for the job which sounds similar to your problem.

In the "old days" I would have done the job myself but there is a chance that horrible black gunge can leak onto a carpet. Luckily my system contains a high dose of Fernox which means the drained fluid was virtually colourless.

regards

Howard

[Bouleversee]

Howard said:

"I had a leaking thermostatic valve in a downstairs room replaced last week by a professional (this was covered by my service plan - £13 a month)."

That sounds very reasonable . Presumably it covers annual service as well as problems such as your leaking trv, a problem I have at the moment, or rather did till I turned the valve off but it must be replaced. Who is the plan with?

[Howard]

Howard said:

"I had a leaking thermostatic valve in a downstairs room replaced last week by a professional (this was covered by my service plan - £13 a month)."

That sounds very reasonable . Presumably it covers annual service as well as problems such as your leaking trv, a problem I have at the moment, or rather did till I turned the valve off but it must be replaced. Who is the plan with?

It's with a local medium-sized firm based near Southampton. They installed a new boiler and it has a ten year guarantee but has to have an annual service which is included in the £13 a month charge. My central heating has needed a couple of maintenance jobs, the other was the replacement of a faulty valve in the airing cupboard. The new boiler did also surprisingly need a new fan which was covered. So all-in-all it's been a good insurance policy.

If you are based within 20 miles of Southampton you will be in their catchment, let me know by PM and I'll give you the contact details, but I'm guessing that their cover will be more expensive if they haven't fitted a new boiler - around £25 a month looking at their website.

But hopefully replacing a TRV is not a big job for a local plumber.

regards

Howard

[Parky]

Consider getting someone in to do the job - get a quote to do the job, then work out how long it would take you to do the job.
Subtract the cost of tools from the quote, and then divide the figure by the number of hours required, and then ask yourself "Am I paying myself enough to do this task?", and "Is it worth getting my hands dirty for £X/hr?"

PochiSoldi

Just carried out the job this morning.
Prepare area, turn off all rads other than the one affected. Drain system. 45 min.
Remove radiator and replace leaking fitting. 30 min.
Replace rad. Inject fernox. refill system. Bleed rad. Check for leaks etc. 45min.
Clean up and test system hot. 30 min.

Just finished before lunch.
Luckily only one leak which pulled up easily without having to remake the joint.

Overall cost a couple of £ for a new fitting and £15 or so for the Fernox, which I was thinking of adding anyway as the system is 10 years old.
Apart from saving money, I actually get a lot of satisfaction from doing jobs like this (when everything goes well of course, which is not always the case).