Water from bath hot tap only luke warm.

amistupid

I have a new Worcester Bosch 38CDi Classic Combi boiler.

The water from all hot water taps is very hot apart from the hot water tap on the bath/shower mixer unit, which only gets luke warm.

This was a problem before we got the new boiler, so I don't think it has anything to do with the combi.



Has anyone got any ideas what the problem is?

jhs14

Presumably the problem is with the mixer unit.

Can you access the pipes coming into the mixer unit, does the hot pipe get hot when the tap is open?

amistupid

jhs14 wrote: »

Presumably the problem is with the mixer unit.

Can you access the pipes coming into the mixer unit, does the hot pipe get hot when the tap is open?

I'll remove the bath side and try and get access to the unit, thanks for your help.

PasturesNew

Is there a sink in the bathroom? Presumably the hot water's hot there.

Ruski

Sounds like you have a TMV under the bath - these can be adjusted if necessary, but are now in the building regs for the safety of those not aware of how hot a bath can be.


HTH


Russ

Hasbeen

Suspect you have 22mm pipe feed to bath hot tap.


Pretty sure combi's are meant to work better with 15mm pipework out as its 15mm cold high pressure in.


22mm out or to bath is more flow less time in boiler = cooler water?

amistupid

Sorry for the delay in replying took ages to remove the 'built in' bath side. :mad:

Under the bath there are 15mm hot and a cold water pipes running to and from a New Team Pressure equalising valve, straight to the bath taps.

When the hot tap is running, the hot water pipe to the valve is hot but the hot water pipe from it is only warm.

amistupid

Bump.

Any plumbers out there?

Does the above post from me suggest that the equalised pressure valve is faulty (it was fitted nearly twenty years ago) and is the reason why my hot water is only luke warm.

If so do I need to replace it with a new one or not.

I have been looking on plumbing forums and there seems to be divided opinion as to whether or not a equalised pressure valve is needed?

It seems that a combi ensures that hot and cold water pressures are equal but the flow rate of the cold supply is greater. I don't want to risk someone being scalded in the shower when water is being used elsewhere in the house.

southcoastrgi

no you don't need it there with a combi & it sounds like it's faulty anyway, tmv's must be fitted on a new install & are recommended on all others, it's so you don't scold yourself in a bath full of hot water, link here & here

AVERAGEJOE_2

First i would check bath taps as expansive ones are usually thermostatic if they bsm (bath shower Mixer) units. If this is the case change the thermo cartridge inside the tap unit.
If it is not a thermostatic unit then check under bath as previously been stated for a tmv unit will look like a big tee unit with maybe red head if so these are not repairable so replace cost around £30 for 15mm.
But it may be the divert handle on the tap letting through cold water even when selecting hot.
THIS IS NOT A PROBLEM WITH YOUR BOILER.

AVERAGEJOE_2

Plus id lose the PRESSURE EQUALISING VALVE you not need this on a new system unless you fitting multipoint combi system.
sounds like this is left over from old boiler system and never removed