Discuss Water not hot after changing Room Thermostat in the UK Plumbing Forum | Plumbing Advice area at PlumbersForums.net

That’s the one to the rads ok the green one is from the boiler so when boosting / turning on this one should run
So one problem (now resolved) is the timer ono the boiler had got out of sync and was runinng 3 hours early so in the evenings the boiler shut down too early everything shut down too early.
So fixed that but still the water is luke warm. The system ahs been running for a couple of hours - heating on Hot water on.
In respect of the two pumps
  • the pipes into and out of the green one are nice and hot - uncomfortable to hold for more than a second or two.
  • the pipes into and out of the red one are much cooler. Warm, almost hot but easy to hold onto for extended periods of time.
Radiators are lukewarm. So it looks like red pump feeds the radiators?
Why are hte pipes not hot
That’s the one to the rads ok the green one is from the boiler so when boosting / turning on this one should run
OK so the red pump drives the rads? - Its hot but you can hold onto it no problem
Rads may only be warm 'cos the need bleeding - I'll check

But since the green one is very hot why is there not a tank full of hot water? (Boiler hot water setting has been on for 3 hours) (Both pumps seem to be runing fine)
Sorry - confused
 
Correct red pump is rads

Have you always had this problem?
 
Correct red pump is rads

Have you always had this problem?
No. System has worked fine for 8+years. It even survived my putting in a new pump.
Started misbehaving some 7 - 10 days ago - long enough after changing the room thermostat so that is, on reflection, unlikely to be related.
Have checked clock; checked on/off settings and all seem fine. Boiler (Ideal Classic NF) thermostat set to 6 (77C - winter setting). seems to fire up when it is supposed to.

I hit the 'Go' button at 15:30 (timer does not kick in until 16:30). Boiler fired up. All good.
At 17:30 both red and green pump pipes are hot - green much hotter than red but red OK (can just about hold it OK; cant hold green). Water from taps is hot but I suspect no volume.
Tried to run a bath and got 6" of hot (but not as hot as it used to be) water before it went tepid.
Previously I could get an entire bath and had to add cold water just to make it bearable.

Just after running the bath, both lights (Hot water and heating) on the boiler control (Dayton) are on but the burners are not alight. (They were alight earlier)
 
Sorry to say need to watch what happens to the boiler / green pump as these shouldn’t be turning off at least for 2 hours as it’s got to heat the water up in the cylinder

Try just turning the boiler control on eg green pump should run don’t run the heating or any hot water if you can and see if the boiler stays on
 
Sorry to say need to watch what happens to the boiler / green pump as these shouldn’t be turning off at least for 2 hours as it’s got to heat the water up in the cylinder

Try just turning the boiler control on eg green pump should run don’t run the heating or any hot water if you can and see if the boiler stays on
Currently
Boiler control Hot water On Heating Off
Pumps Green On; Red Off
Boiler Not alight
Then after 3 or 4 minutes boiler fired up
Then after another 3 or 4 minutes the boiler went out. Green pump still running
Then again 3 or 4 minutes it must have fired up because as I watched it it then went out again.
So what keeps turing it off?

Got to go out now, Will action any further suggestiosn tomorrow am.
Thanks for your help
 
Last edited:
Right that makes sense and that’s good

And how hot would you say the cylinder is about half way
 
Right that makes sense and that’s good

And how hot would you say the cylinder is about half way
Currently very hot. The pipe from the red pump enters half way up the tank and its now as hot as its everb neen in hteh last few days. Mostly this is the pipe that is lukewarm (see earlier posts). It is now (20:05) as hot as the pipe from the green pump

And I now have to go out
 
If you can leave it running as it is eg just heating the store
 
If you can leave it running as it is eg just heating the store
Didn't see this in time and normal heating kicked in (It was seriously cold last night so Im glad!)
I am away for 5 days from this evening so I'll leave heating on its holiday setting (5c) and resume when I get back. (Monday evening). Reluctant ot turn it off altogether as it is supposed to freeze a few tomes over the next few days
Thanks for you help so far
 
OK back early. Too cold!
Boiler (hot water) has been running since early this morning (7am) its now 23:00.
Boiler running fine.
Radiators mid warm
Hot water not as hot as it used to be and still only 6" in the bath - actually only 3" I measured it!. Will leave hot water on all night and check again in the morning
 

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