Dhw problem

[kevoffthetee]

Hi everyone, im new to the forum but in need of urgent help

i have a boiler problem where the heating works very well but the hot water is cooler the higher you have the tap turned on. For it to be hot enough for a shower it only trickles out of the shower head. The 3 way diverter and dhw thermistor was replaced last month to try and rectify the problem but to no avail. I'll say at this point that the radiators dont get warm when I run the hot tap as I've had this problem before and know this would mean the diverter. The dhw flow sensor clicks when drawing water the the burner fires up every time.

I had my retired gas fitter come and take a look at the boiler (chaffeteaux britony combi 80) and he said that it could be down to the pcb so to replace that and while he's at it replace the pressure relief valve as it was slowly loosing pressure. I got the new parts which he fitted and then turned the hot tap on. The water was hot even when the tap was on full flow, job done, or so I though.

I filled the sink and done the dishes then ran a full bath for my daughter, no problem.

I the went up to wash my daughters hair and the original problem returned and I'm now at my wits end. That's now the diverter, dhw thermistor, pcb and pressure valve replaced. Every time a part gets replaced the dhw works properly 2 or 3 times then back to the original problem

WHAT ELSE COULD IT BE???

Thanks for any advice guys/gals

 

[picasso]

You might have cold water crossing over into the hot supply, could be a shower, monoblock tap washing machine or anywhere the hot and cold meet , if you can isolate one thing at a time and see if the problem stops.

 

[kevoffthetee]

Thanks Picasso. I've isolated the mixer taps and the washing machine is cold fed only. The shower is on a mixer tap with a hose and head combined.

I have separate taps next to the boiler and the same problem occurs. This whole proble is recent and the boiler has been running fine for 5 years but given the time and money spent I'm reluctant to settle for a new boiler

 

[dcawkwell]

Sounds like the plate heat exchanger needs cleaning out.
Or could be a wiring fault.
Most of the other parts were probably not needed.

Get someone who knows what they are doing next time
instead of someone who just throws parts at the boiler.

 

[picasso]

You could have a problem with your meter governor, you will need a RGI to check it .

 

[dcawkwell]

You could have a problem with your meter governor, you will need a RGI to check it .

True probably just not modulating and sitting on
low burner.

 

[kevoffthetee]

Would this still be the case if the gas increased as the water flow increased? I'm going to check on this now

 

[kevoffthetee]

A quick update, ivecome down this morning and everything is working. The water is hot no matter what the flow rate and I've tried it all over the house.

Would this suggest anything is working imtermitantly. Thanks again

 

[kevoffthetee]

Sorry to bring this one up again but the boiler is on the blink again. Since the last update I changed the heat exchanger as I got a deal on a well known auction site. The replacement was the newer model which was bigger, I was told this was for better heat transfer and better flow.

Are there any suggests on what it could be next.

Thanks again, kevin

 

[CBF]

sounds to me that it's working correctly, it's a combi of course the water will be cooler the faster you run the tap, you can't have heating & hotwater at the same time, it's a divertor valve not a mid postion valve, if the plate hex is bigger how did you get that to fit, sounds to me you messing with things you shouldn't as you really don't even know how a combi works.

 

[kevoffthetee]

CBF - I know how a combi works, I'm not asking for simultaneous boiling hot water for dhw and chw and I do understand the principle of a three way diverter valve.

The heat exchanger is a chaffoteaux direct replacement that is deeper than the original. The water inlets/outlets are in the same position and the fixings are the same, even down to the rubber seals.

I have has this boiler working for 5 years before having any problems and always had HOT water when the hot tap was fully open. Obviously the water is hotter the slower you run the tap but you still get hot water at full flow. But it sounds like you expect water to be cool/cold when the tap is full open so it sounds like you need more advice.

If anyone else can help I'd be very grateful...

 

[kevoffthetee]

CBF - I know how a combi works, I'm not asking for simultaneous boiling hot water for dhw and chw and I do understand the principle of a three way diverter valve.

The heat exchanger is a chaffoteaux direct replacement that is deeper than the original. The water inlets/outlets are in the same position and the fixings are the same, even down to the rubber seals.

I have has this boiler working for 5 years before having any problems and always had HOT water when the hot tap was fully open. Obviously the water is hotter the slower you run the tap but you still get hot water at full flow. But it sounds like you expect water to be cool/cold when the tap is full open so it sounds like you need more advice.

If anyone else can help I'd be very grateful...

 

[CBF]

so it sounds like you need more advice.

ok i'll ask for some but first i've got to have a bath & finish my homework or i'm not allowed any pudding