Shower hot but bath cold.

[RichT]

Hi. I've been trying to sort out a problem for my son. Central heating and hot water is from a gas combi boiler. Hot water is OK in the kitchen and upstairs bathroom basin. Shower is over the bath with a simple mixer with separate taps for hot and cold and a pull button to divert water to the shower. The shower is hot with no problems but when the divert button is pressed and set for the bath there's plenty of water but it's not hot (with the hot tap on and cold off). The boiler appears to running as if it's heating the water. Any ideas or help would be gratefully received.

 

[PlumbBobBob]

maybe the tap feeds have been swapped i.e cold for hot and hot for cold. try with hot off and cold on.

 

[RichT]

Thanks for the reply Steve.

When only the hot tap is turned on and the shower is working OK when you simply push the divert button back in to change to bath the hot water starts to run cold. Most strange.

 

[Essex Fitters]

Its either the tap it self, OR the heat exchanger is not heating the water in the volume that the bath taps are flowing.

do you have problems heating the house?

 

[RichT]

It's only a small house, the central heating is fine. The kitchen tap and bathroom basin tap both have good flow and get really hot. It may be worth testing the flow through the shower and bath tap to see how they compare.

 

[Essex Fitters]

Think you should be thinking about changing your mixer tap. If that was me i would get a spare tap from the van and put that in place of the hot water tap and see what happens.

Let me know how things pend out!

Is the basin in the same room hot??

 

[dontknowitall]

Presumably the pipe to the tap under the bath gets hot? I'm assuming the shower is piped separately and not part of the bath mixer tap.

 

[fuzzy]

got to be the tap, is it possible to strip down, any blockages?

 

[RichT]

Yes, the basin in the same room is hot.

The shower is not piped separately. It's controlled by the same tap as the bath. The divert button just diverts the flow from the bath outlet to a flexible outlet in the top of the same tap unit. I'd post a picture except I've driven home 80 miles from his house this afternoon. It's similar to the attached picture but a little older in style.

 

[dontknowitall]

Thanks for the pic. Have to agree with the tap being at fault. They just don't make 'em like they used to.

 

[RichT]

Thanks for the replies guys. I think I will have to try and strip it down. I'm off back again in a few days. I'll let you know how I get on.

 

[Essex Fitters]

Presumably the pipe to the tap under the bath gets hot? I'm assuming the shower is piped separately and not part of the bath mixer tap.

From how he has described the tap /mixer its not piped separately. The shower gets how once he pushes the leaver down so its the taps

 

[Essex Fitters]

got to be the tap, is it possible to strip down, any blockages?

Time | Effort - NO!

you still would have to remove and install. May as well me a new tap - Just not viable
1

 

[Essex Fitters]

Will some one change this guys tap, this post is getting on abit! 🙂

 

[stevetheplumber]

most likly cause is the flow rate through the mixer is more than the combi can supply so mixed with cold results in cold coming out
try running just the hot slowly just enough to light the boiler if it gets hot then you know this is the problem
answer is to fit flow reducers or half closed ballofixes
you can be more exact by using a wier cup and thermometer but above will diagnose if this is the problem