Hot water low temperature and pressure. (Diagram, photos and data provided).

e5c3d4 · Post by **e5c3d4** » Mon Mar 06, 2023 3:58 pm

My hot water temperature is low. This varies at different flow rates.

At 8lpm it is around 37deg (c)
At 2lpm it is around 49deg (c)

8lpm is around the max flow rate. It is around the same flow rate / temperature at all taps (upstairs bath / upstairs sink / downstairs kitchen / downstairs toilet sink).

I have attached a diagram of the pipework going to the upstairs bath (the first outlet). This also shows the type, width and length of pipe.

I’ve also attached a photo of this pipework.

All dials on the boiler are set to max (water temp / central heating temp / hot water pre heat on). Boiler pressure is 1.6 bar.

Boiler: Independent C30 combo. Boiler was serviced in Feb. The engineer seemed to think the boiler was fine. The only figures on the report are: Operating pressure: 21.5 mbr min, 18 mar max.

Any thoughts very much appreciated.

Someone-Else · Post by **Someone-Else** » Mon Mar 06, 2023 4:04 pm

I am NOT a plumber or heating engineer, but I must ask, how long has it been like this? and what happened prior?

e5c3d4 · Post by **e5c3d4** » Mon Mar 06, 2023 4:09 pm

I’ve only just taken the readings so i can’t be sure. But I think it’s been the same since I moved in around 12 months ago.

arco_iris · Post by **arco_iris** » Mon Mar 06, 2023 8:15 pm

I am not a plumber or heating engineer.

I suffered with a similar/not the same/don't quite recall now issue for a year or two, not really giving it much thought. Going to fit a new kitchen tap, I went to turn off the mains stopcock, to realise that it was only a quarter open - probably since refurbishing a bathroom some time prior.

After fitting the new tap, I made sure the stopcock was full on - boy did it make a difference! Check yours, both at the meter in the pavement AND under the sink.

Razor · Post by **Razor** » Tue Mar 07, 2023 5:43 am

What flow do you get out of the kitchen cold tap?

e5c3d4 · Post by **e5c3d4** » Fri Mar 31, 2023 12:42 pm

Thanks for the replies received. It’s really helpful.

Following on from my first post, I’ve now done more investigation. I’ve taken flow rate / temp readings at the boiler and just before the taps that feed the shower (to make sure the taps aren’t slowing things down).

Boiler:

Cold in: 15 lpm
Hot out (domestic hot water): 10lpm / 39 deg

Bath (pre tap that feeds the shower)

Cold: 15lpm
Hot: 8lpm / 35 deg

Does this suggest a problem with my boiler? As above, a recent service didn’t flag anything. I’d say it’s only 5-10 yrs old.

Thanks again.