Boiler flow temperature way too low!

[Meatyfool]

Hi,

I used to (pardon the pun) be really hot in keeping my boiler tip-top but then kids, middle age and existential meh strikes …

I know, I know, I should have had my boiler serviced annually, but here I am wishing I had.

Boiler is Worcester Bosch 24i system boiler vintage 2007.

I set the boiler temperature to 5 which is 74 degrees - I am only getting 45 degrees at the flow pipe. Needless to say it’s been a while since a heard the condensed water gurgling down the drain.

It isn’t sludge because I am not getting noises in the heat exchanger and there aren’t any cold radiator bottoms.

I have a smartphone flir camera that I can use to help me balance the radiators but that seems pointless until I can get the system temp up to where it should be.

HWC is megaflow.

Hoping it isn’t something terminal in the boiler but expecting that there is a fault with a sensor in there.

FYI. Regarding Legionnaire’s - we regularly use the immersion to heat the water when we run out and on a sunny winter day I’m certain we can get the stored water up above 60.

Hope you can help,

Meatyfool..

[88V8]

I set the boiler temperature to 5 which is 74 degrees - I am only getting 45 degrees at the flow pipe.

Our 1991 boiler was never serviced in 31 years... and never went wrong... luck of the draw...
Presume it's the boiler stat... have you tried the troubleshooter ?

V8

[DrFfybes]

If you turn the boiler up to 6, does it get warmer?

Can you turn it to eleven?

Paul

[Mike4]

Hi,

I used to (pardon the pun) be really hot in keeping my boiler tip-top but then kids, middle age and existential meh strikes …

I know, I know, I should have had my boiler serviced annually, but here I am wishing I had.

Boiler is Worcester Bosch 24i system boiler vintage 2007.

I set the boiler temperature to 5 which is 74 degrees - I am only getting 45 degrees at the flow pipe. Needless to say it’s been a while since a heard the condensed water gurgling down the drain.

It isn’t sludge because I am not getting noises in the heat exchanger and there aren’t any cold radiator bottoms.

I have a smartphone flir camera that I can use to help me balance the radiators but that seems pointless until I can get the system temp up to where it should be.

HWC is megaflow.

Hoping it isn’t something terminal in the boiler but expecting that there is a fault with a sensor in there.

FYI. Regarding Legionnaire’s - we regularly use the immersion to heat the water when we run out and on a sunny winter day I’m certain we can get the stored
water up above 60.

Hope you can help,

Meatyfool..

I hate to suggest this but I think you may have run into one of the (many) reasons some of us gas bods hate Worcesters.

I'm no expert on Worcesters but one of their more popular models has a heat exchanger that clogs up on the gas side without regular servicing. This, IIRC shows up as a progressive reduction in heat output. The electronics and the gas valve recognise the gasways getting ever more restricted and reduce the gas consumption to compensate and keep combustion correct.

You can check this yourself by reading your gas meter twice, two minutes apart and doing a bit of arithmetic to work out the rate of gas consumption and therefore the power being consumed. Then compare the measured power consumption of your boiler with what the data plate says it ought to be.

Also, check your warranty. Some of the Worcester warranties are/were really long!

[Meatyfool]

Many thanks for the replies.

DrFfybes, respect!

Mike, a true TMF/LF hero.

Your assessment seems to match perfectly. What do you mean by clogs up on the gas side? I’m guessing that the heat exchanger has the gas burning on one side of the exchanger and the water on the other. Plenty of stuff on the web about sludge on the water side but nothing I found about issues at the gas side.

The really important question I need an answer to is - is it terminal? Can it be cleaned as part of a service? I know you gave up on installs when the refg changed - I really need to hunt someone out the same. Too many HE will just go for a replacement.

Once again, many thanks.

Meatyfool..

[Mike4]

Your assessment seems to match perfectly. What do you mean by clogs up on the gas side? I’m guessing that the heat exchanger has the gas burning on one side of the exchanger and the water on the other. Plenty of stuff on the web about sludge on the water side but nothing I found about issues at the gas side.

Yes water one side, burning gas on the other side inside the heat exchanger (HE). The gas ducts get clogged up and there are many threads in the Combustion Chamber discussing ways to unclog them. Most methods involve plugging the condensate drain and filling up the gas side of the HE with Coca Cola, which apparently loosens and dissolves it. Not something I'm willing to ever try given all the time it takes, when Worcester will (usually) do it for you under their ten year heat exchanger warranty, or if out of warranty under their fixed price repair scheme for £300 (ish). And of course because lots of people think a boiler service should cost sixty quid and trying to bill for four hours spent unclogging a Worcester HE rarely goes down well! (This is one of the several reasons I prefer not to work on Worcesters.) (Ok, NEVER!)

The really important question I need an answer to is - is it terminal? Can it be cleaned as part of a service? I know you gave up on installs when the refg changed - I really need to hunt someone out the same. Too many HE will just go for a replacement.

No it isn't terminal. Seriously, call Worcester themselves. I hear of cases where they fit whole new heat exchangers under the £300 fixed price repair plan thing, even though the price for the HE alone to people like me is reputed to be more than £300.

All my comments apply to the vertical cylinder type of Worcester HE, widely nicknamed the 'kebab' HE as it is the shape of the disgusting lump of warm-ish lamb rotating behind the counter in late night kebab shops. I'll see if I can find an image...

[Mike4]

Here we are, best i could find. Leaking water at the top like this is a common fault too.




https://bryant.org.uk/images/screenshot-2023-12-01-at-07.36.10-840.jpg

[Dod101]

In this weather the answer to the op’s problem is to call a heating engineer and get it fixed. Why on earth would you worry about what is wrong if you are without a working boiler?

Dod

[Meatyfool]

Dod101,

Working and heating the home just not to the temp I would prefer. Heat exchanger just not getting up to the 75 it should be.

Mike,

Many thanks again - I have the kebab. Will make the calls. Chimney being swept tomorrow so an extra heat source!

Meatyfool..