Hot water not coming through all outlets as hot - ASHP issue?

[crazypup]

Hi there, I'm hoping for some advice:
We have an ASHP fitted about 2 years ago and for the past year(ish) we have had problems with the water coming out tepid at best, for some outlets but others have no problems at all. So en-suite shower has never had a problem but the taps are v temperamental. Other shower v temperamental but the taps are usually fine. All very frustrating in a house with multiple taps/showers but we can only use one shower and sometimes hunting around the taps to find hot water! All taps have mixers on them and most are less than 8 years old. We are not even trying to run multiple showers at the same time. We have a Mixergy cylinder. Please help!

 

[JohnD]

Put a thermometer under the tap and test the actual temp. Showers tend to feel cooler as the spray loses heat to the air.

Is it worse in winter?

What colour is your hot-water cylinder?

Are the pipes insulated? And short?

 

[crazypup]

Hello John, thanks so much for your swift reply. One shower starts off hot (sometimes) then cools to tepid. the other shower is always hot so that we have to reduce the temp to comfortable so you can feel the difference and now my kids only use our shower! not worse in winter as we've had the problem for coming up to a year now.
The Mixergy cylinder is a white one.
Pipes all insulated. Not sure what you mean by short as pipes have to go all over the house and it's very strange as the bathroom with the tepid shower has boiling hot taps.

 

[Daveydub]

Could be a faulty check valve on a shower.
If you run one of your not so hot taps and then wander around and feel your shower valves is one of them particularly cold?

 

[JohnD]

I was thinking that a long pipe to a distant bathroom will lose more heat as the water travels along.

 

[crazypup]

Hi D - I'm going to get a plumber to check valves as I don't have a clue. one plumber suggested that cold water might be drawing back (??) or something and stopping the hot coming through so this then maybe a mixer fault? but house if full of mixer taps and tricky to isolate. he did shut two off and still have the problem.
And yes John I would have thought that too but we never had an issue with this until the ASHP was fitted - and a pressure reducing valve fitted more recently if that means anything? also odd that one bathroom has the hot shower/cold tap and the other on the other side of house has the opposite. All very frustrating!

 

[crazypup]

And yes D I will try as you suggest tomorrow and pray!

 

[Daveydub]

It will be a temperature controlled mixer so shower mixer not basin mixer.
While running a not so hot tap you may hear something if you put your ear to temperature control knob.
If they are exposed valves the temperature check by feel will be easy but if they are concealed and you can access the pipework feeding them then feel temperatures on the pipework.

 

[crazypup]

Okay so you think it's definitely a shower mixer not any basin mixers? I'm adding some pics as we have concealed mixers on two showers and a shower mixer on the bath as well - no pipes are accessible as they are all behind tiles or panelling. I think one shower has the exposed valve?

 

[Daveydub]

Start with the easy exposed one. Run shower till body is hot, usually on left hand side.
Run a not so hot tap. Cold water flowing through the shower will rapidly cool the LHS of this shower.
If it is not this one then you will have to repeat by pulling the faceplate forward on the concealed valves and getting a finger in behind to feel the connections. I would do them one at a time starting with the one nearest to the problem area.
That putting your ear to temperature control knob while tap is running is worth a try.
Just a thought though, you don't have any blending valves anywhere to limit temperature at basin or bath taps do you?
These would also count as mixing valves