Boiler supply from bath

[andrewjsmith]

We recently had a new Vaillant boiler and new rads installed. The boiler is now in the bathroom. But the boiler fires up when the bath COLD tap is switched on...

...the plumber said this was because he couldn't get to some other pipe to supply the boiler - so used the same pipe as the bath cold. That would be fine, but the mixer shower in the same bathroom now doesn't get hotter than lukewarm. It was hotter with the 50 year-old old boiler.

I'm concerned that the cold for the shower is drawing water from the boiler and this is why not enough hot water is getting to the shower. Can anyone confirm this fear and/or suggest a solution?

I'd like to get the plumber back to fix it but am out of my depth and don't want to be charged for maybe 'fixing' a shower that is fine.

Thanks.

 

[newbie1]

this numpty has cocked it up good and proper
first question was he a gas safe registered engineer as if he wasnt your house ins will be voided and you also have no one to report him to
the boiler should never fire up if you run the cold tap
the vaillant takes a feed from the cold main and then runs a 15mm pipe to the hot supply and my guess he has connected the hot supply somewhere into the cold feed for the bath

 

[andrewjsmith]

He is Gas Safe. We're calling him again today - have low hopes.

The plumber is coming again tomorrow to take a look. It took a while but he began to admit the way he's set it up would affect the temperature/flow coming out of the shower.

He mentioned fitting a valve to the cold into the shower to slow its flow; but that's a symptom of a larger issue so I insisted we have a dedicated feed from the mains. If he tries to wriggle out of it tomorrow, he's out the door.

 

[Bernie2]

GasSafe is for gas fitters and Plumbers or central heating engineers wanting to work on gas, even chimney sweeps and double glazing fitters have to be GasSafe registered or where CORGI.

It doesn't follow that a GasSafe registered fitter knows a lot about central heating.

 

[helpsy]

Don't go on what he is telling you, ask to see some proof/verification.

 

[andrewjsmith]

If you're talking about Gas Safe verification - I checked his reg no. on the Gas Safe website and it checks out for his company name.

 

[54ab]

and photo

 

[newbie1]

was he doing the job for his company or as a private
if for the company then call them direct if he was doing it as a side job he has to have his own registration as his work one wont cover it

bernie if he has ccn1/cen 1 then he would not need plumbers knowledge to fit the boiler as there is only one place the hot goes and that is into surprisingly enough the hot feed for the taps etc
basic combi principal
cold feed to boiler hot flow out to hot supply
he would need to be a complete chancer to have run the hot to the cold taps
combi can only work when it detects flow through an external outlet and that can only ever be the hot flow

 

[Jimbob]

the guy has obvious fitted a combi boiler and just connected it up the easiest way possible. The boiler could really use being as close to the first point of the mains as possible.

Just out of intrest have gone from open vented to unvented hot water? this could be effect the shower.

When you run the bath colder tap the boiler fires up, but does it come out hot? the drop in pressure could be triggering the flow switch

prob dead easy to sort but i cant get my head around it without pictures

 

[stevetheplumber]

We recently had a new Vaillant boiler and new rads installed. The boiler is now in the bathroom. But the boiler fires up when the bath COLD tap is switched on...

...the plumber said this was because he couldn't get to some other pipe to supply the boiler - so used the same pipe as the bath cold. That would be fine, but the mixer shower in the same bathroom now doesn't get hotter than lukewarm. It was hotter with the 50 year-old old boiler.

I'm concerned that the cold for the shower is drawing water from the boiler and this is why not enough hot water is getting to the shower. Can anyone confirm this fear and/or suggest a solution?

I'd like to get the plumber back to fix it but am out of my depth and don't want to be charged for maybe 'fixing' a shower that is fine.

Thanks.

possibly just needs a non return vave near the take of point it doesnt realy matter where the main is teed from to feed the combi first tee on the incoming is preferable but not always practical especialy with an upstairs install
where ever you put it its before something

 

[andrewjsmith]

The company itself is Gas Safe registered and this plumber owns the company so that's all fine I think.

The problem with drawing the water from the bath pipe is not that the boiler comes on when the cold tap is on - that's sort of superficial to us - but that the shower is only luke-warm.

There is a proper feed in the bathroom which went up to the attic where the old tank was.... the plumber just didn't use it because it was slightly harder to access in the corner under the bath.

The cold tap on the bath doesn't get hot; reckon the drop in pressure or flow is causing the boiler to start up.

When the very very basic mixer shower is on, the cold side is drawing some water away from the boiler and, as a consequence, the boiler is producing less hot water for the hot side - so: lukewarm shower.

Though a non-return valve between the cold tap and the boiler might sort the problem of the boiler coming on pointlessly - it doesn't solve the shower problem.

And some kind of valve on the shower to restrict the flow to the cold side might solve the shower temp problem for now but, further down the line, if we got a new shower or bathroom, I suspect we'd have to take that off and do it properly? Also, wouldn't this basically just slow the flow of cold and so lessen the pressure coming out the shower? I'd prefer hot and cold both belting out maximum pressure and I set the temperature to how I want it without sacrificing any pressure.

 

[quality]

Is there any hot water from your kitchen sink tap, possibly bath taps are opposite way round - shower temp problem probably due to lack of hot water flow at a decent temp from a average combi (ps combi`s are c**p in my opinion)