Low hot pressure on tap in bathroom

R

Richard Lindsay

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Stirlingshire
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Hi folks,

So I have a mixer tap in my bathroom and when I move it to the hot position the water trickles out. It never gets hot, I assume because the flow is not great enough to kick the combi boiler on.

I replaced the tap thinking it was that, same problem.

If I move the tap to the middle position the water kind of fobs out (can't think of a better description). It is cold and gets faster the more i move the tap to the cold position. The only other tap in the house is in the kitchen and it is fine.

I think the hot pipe has a blockage but wanted some advice first.

Cheers for your time.
 
Something is restricting the flow to the hot tap ,if its from a combi it should virtually be at mains pressure. Any isolation valves on the supply pipe to tap ?
 
Are they red handled gate valves ,notorious for not being fully open internally ,when you think they are.maybe not under sink but elsewhere on the supply ? What valves are they in vanity unit ,are they fully open ? You could remove tap tail from iso valve and check flow from the valve is good.
 
They're compression fittings on plastic pipe with a flat head screw controlling the flow. Ive had the tap running, turned the valve off and the tap has completely stopped. When i open it again fully i get the trickle. The pipes go under the floor from there, under the kitchen and then to the boiler. I might need to just wait until we have the bathroom done later in the year to fix the issue unfortunately.
 
Up to you how to proceed Richard ,but you would appear to have a restriction on the hot supply pipework to that tap ,maybe the isolator or upstream of it.
 
You leave the isolator on the hot pipe ,disconnect what is connected to the isolators outlet.maybe take a pic and post here so you can be given exact instructions rather than broad brush .in a nutshell ,with tap not connected to iso valve ,its outlet side will produce a flow of water when valve is turned on .so if you connected a flexible hose to it for example. Directed to a bucket then open the valve ,you can see easily what kind of flow is coming thru the iso valve as it runs into bucket.
 
Ok cheers, I'll try that tonight.

This is only testing upstream of the valve though, right?

I'd need to replace the valve to check if the valve was faulty?
 
Water coming from iso valve at a trickle ( like you get from hot tap ), would Indicate a problem with the valve ,or upstream of it. A good rate of flow from isolator would tell you that the onward pipework and tap are the issue.
 
Cheers

If it's an issue with upstream of the valve, i.e in the pipe, is there anything i can do to try and unblock it without ripping the bathroom to bits and replacing it?
 
Its very unlikely that you have a blocked pipe ,not impossible ,but highly unlikely. Did original tap ever work properly ? First thing is to focus on the iso valve that you have in vanity unit and go from there.
 
Could it be that your tap is not suitable for low pressure systems? I've definitely seen that before where cold is mains pressure so works fine - well I've seen it on showers and pretty sure same would apply
 
23vc said:
Could it be that your tap is not suitable for low pressure systems? I've definitely seen that before where cold is mains pressure so works fine - well I've seen it on showers and pretty sure same would apply
Click to expand...
He has a combi boiler 23 vc
 
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