Heating always on and reduced hot water temp

[oli1012]

Hello.
I wonder if someone can help.

We have noticed 2 issues in our house over the last couple of weeks . We have a Glow Worm Ultracom 24cxi combi boiler and have never had problems with it previously

1) central heating always/near constantly on. We have 2 small radiators and a towel rail none of which don't have a TRV which are the ones that stay on. Obviously able to control the other ones via TRVs.

2) Reduced hot water temperature from taps. Kitchen tap next to boiler approx 43. Upstairs basin tap around 38. Shower mixer tap around 37. The boiler engineer we had put suggested this is due to drop in air temp leading to reduced water in temp from mains hence drop in hot water temp however this doesn't really make sense as this has not occurred in previous winters

What have we done:
Had boiler checked by a heating specialist - no problems with the boiler identified. Their suggestion was that it could be the wireless thermostat/controller and interference from wireless router which I really do not think is the case. Have also changed the batteries in the thermostat which made no difference.

I don't think it's a problem with the thermostat within the shower mixer tap.

My layman's thoughts were could it be a diverter valve issue or could it be related to high water pressure as we also have pipes that bang when water is turned off which possibly indicates water pressure is too high.

Please let me.know any advice or guidance.

Thanks

oli

 

[John.g]

Don't understand your first issue, are you saying that 2 rads do have TRVs and the towel rads don't?, the boiler will stay on if a faulty zone valve, have you got these rads zoned?.

Best take a few flow measurements.
My mains temp is 10C just now so assuming yours similar then a 24kw combi should give 6.9LPM at 60C.
10.4LPM at 43C, 12.3LPM at 38C and 12.7C at 37C.
Run anyone of these taps into a container for exactly 15 or 30 secs and measure into/with a 1litre container, X by 4 or X 2 as applicable to give the flowrate in LPM.
Post back.

Also ensure DHW temp control, if installed, turned to max setting.

 

[oli1012]

Don't understand your first issue, are you saying that 2 rads do have TRVs and the towel rads don't?, the boiler will stay on if a faulty zone valve, have you got these rads zoned?.

Best take a few flow measurements.
My mains temp is 10C just now so assuming yours similar then a 24kw combi should give 6.9LPM at 60C.
10.4LPM at 43C, 12.3LPM at 38C and 12.7C at 37C.
Run anyone of these taps into a container for exactly 15 or 30 secs and measure into/with a 1litre container, X by 4 or X 2 as applicable to give the flowrate in LPM.
Post back.

Also ensure DHW temp control, if installed, turned to max setting.

Hi there,

There are two small rads and a towel rail none of which have TRVs and these are always on at the moment whereas previously they would only come on when the central heating was triggered by the room temperature being below the temperature set on the thermostat for that time.
There is just one zone/circuit for the house.

I will take the flow measurements later when I get home. Is this just from the cold water tap or do I need to measure at all those temperatures?

 

[John.g]

This could be the end switch (which switches in the boiler) on the Zone valve causing the boiler to run continuously, although the other rads should be warm as well except that the TRVs have shut right down.
If you can have a multimeter or even a phase tester can tell you what to check.

Just take it from any HW tap you like, measure its temperature as well. You can take the cold water temperature if you want to get a accurate cold water temperature for doing the calculations if different to my 10C.

 

[oli1012]

Hi.

I don't have a multimeter so not done that yet.
Flow at approx 40 degs from tap (boiler set to 62) was 7.5LPM. Cold water from cold tap approx 9.5LPM. It is an old house with narrow pipes, unsure if this makes a difference.

I also tried switching the boiler to the 'hot water only' mode as opposed to being off completely or being in 'hot water and central heating mode' however the heating remained on overnight despite this - seems strange.

Also see below a video which shows what seems to be a rattling/clicking/loose body sound that seems to be coming from inside the pump which has only started happening over the last week or so.

Thanks.

 

[oli1012]

see video below showing clicking noise

 

[John.g]

Assuming ita a combi boiler then you can set the DHW temperature to whatever you require. tap icon. If its set to 40C then it will deliver 7.5LPM (at 40C) as it only requires 15.7kw to do so. If its set to 62C? then it should still deliver 7.5LPM at almost 59C. ( at its max output of 25.5kw to HW)