No Hot Water - Only Lukewarm

[Michael01474]

Just after a bit of additional advice regarding a problem we have with our hot water.

We have a Potterton Performa 28 (about 4 years old). Recently the Hot water hasn't been getting hot at all, only vaguely lukewarm. The CH which I've only just put back on seems to be fine.

I had a local Corgi engineer out on Monday and he told me that there were a few things wrong with it (Diverter Valve,Pressure relief Valve and a couple of minor leaks). He suggested I call Baxi as they would probably do it cheaper and they would have the parts on the van.

Baxi (sub-contractor) came out today but their engineer said that the diverter valve was fine and that it is the DHW temp sensor. I had to mention to him that he was actually pointing at the Central Heating sensor and that I'd already replaced the DHW temp sensor and it hadn't fixed the problem. He told me that the new sensor could be faulty and that he would still change it. Unfortunately he wasn't carrying any parts with him and has to go away and order them (back sometime next week).

Anyone have any of their own views? I've paid Baxi now so don't really have any choice but to let them fix it but I'd like to have a clearer picture in my head of what it might actually be for when he returns (he may fix it of course - I shall have to wait and see)

Many Thanks

Michael

 

[timmy74]

does the boiler fire up then shut down and keep doing this while hw running? possibly sec heat ex blocked

 

[Michael01474]

Boiler fires up fine, then shuts off when it gets to 80 on the front panel (does get to 80 quite quickly mind). It then comes back on when it goes down to 60.

 

[kevplumb]

Boiler fires up fine, then shuts off when it gets to 80 on the front panel (does get to 80 quite quickly mind). It then comes back on when it goes down to 60.

back to the topic sorry about that

is this just on h/w or c/h as well

 

[Michael01474]

Seems to just be HW, heating seems fine. Burnt my hand on the towel rad just the other day

 

[kevplumb]

chances are the domestic heat exchanger is clogged with system debris (bleeding censor) possibly just needs a flush

having said that a new heat exchanger is dirt cheap if you pardon the pun (says a lot)

 

[timmy74]

you heard of something called DS3 or DSR made by fernox, this is a bit of decent gear for flushing heat exchangers out. normally sold in b n q

 

[kevplumb]

DS3 will eat the flaming thing DS 40 good solid system might do it

 

[timmy74]

couple of teaspoons of ds 3 be ok..

 

[kevplumb]

oh yeah and how are you gonna get it in the system

e mail me

 

[timmy74]

take heat exchanger out

 

[kevplumb]

so you might ass well change it you gonna clart aboot for the sake of £30

 

[timmy74]

30 quid knocky off like

 

[kevplumb]

err no i get them for 25 inc i suppose the price reflects the quality

 

[Michael01474]

Well, it's now nearly a month later and I'm still without hot water. Baxi have been next to useless (it takes them a week to dispatch parts to their sub-cons) and are not interested in my complaints or doing anything to help me. Third engineer came out yesterday to fit a DHW Heat Exchanger but it didn't cure the problem. They now think it is the diverter valve.

What I'm interested to know is is it possible to check the diverter in case the diaphragm is split (from what I've been reading this could be the issue). If so is it possible to change it (£6 part I believe) so that I can get some hot water over Xmas? I'll still let them come and replace it but that's not going to happen now for at least 2 weeks (not including Xmas obviously)