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

[e5c3d4]

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.

 

[gmartine]

It's low, @ 2-3 l/m you should be getting the max temperature of 64 degC. Is it on with central heating?

​

 

[e5c3d4]

No. That’s only with the hot water on.

 

[ShaunCorbs]

What’s the cold water flow rate ?

 

[e5c3d4]

No. That’s only with the hot water on.

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.

 

[ShaunCorbs]

Tbh no sounds about right for a 30kw boiler if the cold water is around 7-8 dc temp wise

Bath is lower due to bigger pipes eg 22mm and 15mm supplies

The boiler cold valve is open fully isn’t it ?