Combi boiler -hot water in basin, lukewarm in bath /shower??

Combi boiler -hot water in basin, lukewarm in bath /shower??

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adibear

Original Poster:

1 posts

85 months

Wednesday 22nd February 2017
quotequote all
Hi guys, a total noob in every respect posting in here for the first time. Quick background - I am 26, have just purchased my first home on my own in London and have literally 0 experience, 0 husbands, and 0 mum and dad around to help me understand absolutely anything DIY related that is going on in my house smile So if anyone has advice on this matter please explain it to me as you would to a 5 year old!

I just had a new bathroom fitted, and until two days ago, all was fine. I was getting blissfully boiling hot water out of my shower, the bath taps and my basin taps. Then on this past Monday, my energy company came round to exchange the pre-payment gas meter I had with a dummy one, as they are installing a smart meter the following week. The engineer who fitted the meter did check on the boiler, but as far as I know, didn't mess with it much or change anything (It's a Baxi combi boiler, 9 years old). The dummy meter is a standard credit meter that requires no topping up.

However, a couple hours after he installed the dummy meter, I went to take a shower and noticed the water only started off as nice and hot for the first 10 seconds or so, then cooled down, then warmed back up slightly to lukewarm, where it stayed like this for 15 minutes until I finally grew frustrated and turned it off. It's a thermostatic shower, and all the taps are mixer. However - when I turned on the sink tap in the bathroom, the boiling water came out just fine. This baffled me, as both the shower and the bath tap are doing this odd lukewarm business, but the sink tap is doing just fine. I then decided to watch my boiler while I turned on each tap. I set the max hot water temp on the boiler and turned on my hot water tap on my sink. It heated up within a minute to 69 (the max on my boiler) and stayed there for 5 min until I turned it off. I then turned off the sink tap and tested the shower - the boiler, after 10 minutes, only made it up to 55-58 degrees and never reached the 69/70 my sink did. Also, the lukewarm water the shower was giving me was definitely not accurate to what the boiler said - it certainly wasn't 55 degrees. The bath tap was the same story as the shower - only the bathroom sink seemed to be behaving.

This morning I had national grid send an engineer over as my radiators weren't working either (they have never been working since I moved in in January, so they have nothing to do with the hot water issue seeing as how the hot water was fine on the prepayment meter). The engineer got my radiator and hob up and running and confirmed there was no problem with the actual gas supply. When I told him that the only new variable is the new meter, he shrugged and said "I doubt it's your meter at all," even though I told him that's the only thing that has changed. After feeling the water, he actually said this tepid lukewarm water out of the shower is "probably the best you're going to get." I told him no way that is true, seeing as how I know it was previously capable of delivering hot water under the prepayment meter. He then suggested I get the boiler serviced. Again - I would like to avoid this as so far all the lights have been on and fine with the boiler and until the meter changed, nothing was wrong.

I called up my plumber who fitted the bathroom and he was baffled. He said the pipe that connects the sink and the shower is one and the same, so no clue why only the shower / bath would be affected and not the basin. He did say that the hot water for the shower came from the mains, whereas the hot water for the sink and bath taps came from the tank - but again, my bath tap is behaving the same as my shower, so not sure what that has to do with anything?

I called up Baxi and for the low price of several hundred ££££ I can buy myself a whole warranty and service on the boiler ready to come to my house tomorrow... so on and so forth. But I wonder if my best bet is to wait until the new meters are fitted on Monday and then give it a few days and see if it acts up again. Has anyone ever heard of this problem before, or could advise on next steps? I really would like to avoid forking out the fee for the boiler service, given that I know it performed beautifully before the dummy meter.


Any help is hugely appreciated, tx, Adi x

V8RX7

26,762 posts

262 months

Wednesday 22nd February 2017
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I doubt any of us can be much help however I would suggest:

If it was anything to do with the meter (and I'd doubt that it was) then it would affect all taps.

I would only get a plumber (rather than a warranty) to look at it.

Tom_C76

1,923 posts

187 months

Wednesday 22nd February 2017
quotequote all
It may be the boiler isn't getting enough gas to heat the water enough at the rate the shower or bath taps can draw it at. Combi heats the water as it flows through so if heat isn't enough for flow... only a guess though.

j4ckos mate

3,009 posts

169 months

Wednesday 22nd February 2017
quotequote all
I've just had a similar situation
No hot water downstairs.
But ok upstairs.
The combi boiler wasnt firing up the rocker pin wasn't getting activated because the rubber diaphragm had stretched
I wonder if this is the same for you and the extra taps being turned on is enough to fire it up

Best get someone in

silversurfer1

918 posts

135 months

Wednesday 22nd February 2017
quotequote all


Almost certainly a flow rate issue or possibly the starting of a scaled plate H/E

The temp on the boiler you are reading will be primary flow temp not what is being delivered to your taps.

A combi boiler will only deliver hot water at a certain flow by a certain amount of temperature gain slow the flow and you will increase the rise in temperature.

Often people complain that the basin is ok but the bath is rubbish and this is because the basin tap is a lot smaller and so naturally restricts the water giving a better temp rise.

Just try slowing the bath to half of what it is currently and leave it to run like this for a couple of mins remembering when you have adjusted the tap the change won't be instant as you have to empty the pipe from the boiler to the tap.

The shower may be a separate issue possibly thermostat try the above first

good luck

ss

jshell

11,006 posts

204 months

Wednesday 22nd February 2017
quotequote all
silversurfer1 said:
Almost certainly a flow rate issue or possibly the starting of a scaled plate H/E

The temp on the boiler you are reading will be primary flow temp not what is being delivered to your taps.

A combi boiler will only deliver hot water at a certain flow by a certain amount of temperature gain slow the flow and you will increase the rise in temperature.

Often people complain that the basin is ok but the bath is rubbish and this is because the basin tap is a lot smaller and so naturally restricts the water giving a better temp rise.

Just try slowing the bath to half of what it is currently and leave it to run like this for a couple of mins remembering when you have adjusted the tap the change won't be instant as you have to empty the pipe from the boiler to the tap.

The shower may be a separate issue possibly thermostat try the above first

good luck

ss
This is exactly what we have to do with the bath taps - throttle them back to get an adequate temperature! Sinks are fine.

megaphone

10,694 posts

250 months

Thursday 23rd February 2017
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Did they turn the water off at the stop cock when they fitted the meter? Maybe the flow had been 'throttled back' at the incoming stop cock to help raise the temperature, now it's full on and the flow is too much?