Extending Hot Water Feeds to New Extension

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Hi

I have recently built a kitchen and have extended the central heating into it and it works fine.

The problem i have at the moment is the hot water to the taps. I extended the existing run from the existing kitchen (at the back of the house) to the extension and the hot water does not seem to reach the tap. If i turn the tap on in the existing kitchen it will come out hot, but not without.

Ultimately the old kitchen will be decommissioned, and the pipes to the existing taps capped off/removed and i am worried that i will not be able to get hot water into the new kitchen.

Is there anything i can do, pipes are under the floor and under units.

Lee
 
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What make and model combi, did you run new pipes in 15mm copper or plastic. Small flexes to taps? Standard ballofix valves for isolators and not full flow ones
 
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New pipes are in plastic
Flexes are 30cm I think
I used Speedfit isolators which I do not believe are full bore (at least not marketed as such)
Boiler is a Baxi 105e I think
 
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New pipes are in plastic
Flexes are 30cm I think
I used Speedfit isolators which I do not believe are full bore (at least not marketed as such)
Boiler is a Baxi 105e I think
Baxi 105e do a search on here for water venturi that will be your problem it will have fell apart and need changed 15 quid part
 
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Funnily enough I had that exact part replaced about a year ago when there was no hot water in the shower. Shower is still working though/? Could it be the same thing?
 
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Ive not checked the boiler firing up yet, I would guess that it doesn't though tbh
 
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Combi’s sense the flow and use that as a demand for heat - run may be too far / pipes too resistive to the flow to be enough to meet the threshold to trigger the demand? Just a thought.
 
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Just checked the boiler, does not go on when the tap is on. This one is approx 6m away from the one that does turn the boiler on.

There is another tap going in about 2m from the original, I've just put the sink in but need to sort the tap out will be interesting to see if that triggers the boiler

Could it be the valves that I have used I wonder?
 

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What's the flow like at the new tap compared to the old? Time the filling of a know-size bucket. As others are suggesting it sounds like a flow-detection issue but before you blame the boiler or tap/plumbing it'd be worth ensuring the new tap (and plumbing to it) is drawing adequately to rule it in or out.
 
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Ill get a bucket and time it, i would suspect its lower in the new one but will check for sure
 
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If the boiler isn't firing up when you open the hot water tap, then the boiler isn't seeing the demand, or there isn't enough demand to trigger the differential switch.

There are a few reason that could cause this, it could be the valves but it really should be unless your mains water pressure/flow is poor. The 105e's are known for issues around the venturi/diverter/differential valve as suggested, when they get older they can become less sensitive - for lack of a better way to describe it - and sometimes need more flow to push the pin out far enough to trigger the switch.

If it is the pressure switch/diverter in the boiler then the valve may need serviced. Easy to check, get someone to turn on the hot water and check to see how far the front pin extends, sometimes they extend but not enough to activate the microswitch. These valves are very serviceable, lots of parts kits & vids available showing how.
 
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Just out of interest on the Venturi side of things, this was definitely broken before and the symptom was the shower not getting any hot water. Currently the shower is still getting hot water, would this mean the the venturi is OK?
 

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