Hot water only activates on certain taps

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Hi all,

I hope everyone is well!

I was wondering if anyone could point me in the right direction. I have a i-mini c24 combi boiler that was here when I move in to the flat in April. The boiler was only installed two years ago apparently.

Ever since I've moved in the showers hot tap which is a round mixer affixed to the wall has never engaged the boiler, so I've been running the bath hot tap at the same time to kick it in to gear. As I'm having a new bathroom fitted next month I was thinking timescale and loss of pressure although it seems fine when showering, hoping it'll fix it.

I did get the boiler looked at previously and had the turbine replaced that activates the hot water but this didn't fix it. Hence the wait and see approach.

Anyway, I replaced the kitchen tap this evening, the tab naturally has a lower pressure, the last one pretty much flooded the kitchen it was so powerful, but the same is now happening, no hot water unless I have another hot tap on somewhere else. In my case the bathroom.

Has anyone else experienced this? I was thinking of reducing the diameter of the pipe work (I think it's 15mm at the moment) to increase the pressure but to be honest this isn't my area of expertise.

Any pointers greatly appreciated.

Many thanks, rich
 
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CBW

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Are you now saying the kitchen tap replacement doesn’t activate the boiler?
 
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Correct, it's now both the shower and the kitchen tap.

Whereas the bath hot tap and the sink does activate it. It kicks in around 85% open. I'm assuming the pressure isn't good enough. But no idea how to fix it, currently.
 

CBW

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Any isolation valves underneath for the kitchen sink tap? You also may have bought a tap that requires a minimum pressure to operate, this could also be the same for the shower.
 
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Correct, it's now both the shower and the kitchen tap.

Whereas the bath hot tap and the sink does activate it. It kicks in around 85% open. I'm assuming the pressure isn't good enough. But no idea how to fix it, currently.
When it kicks in at 85% open just run the water into a container for exactly 30 secs, measure this with a 1 or 2 liter milk bottle or whatever, X2, this gives the flowrate in LPM, post back.
 
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It runs straight through from the main shut off valve from outside. It's only a meter away from the valve.

The old tap had so much pressure it would spray all over the kitchen. It was connected via copper pipe and the new via the Flexi pipe, but it isn't twisted or at any funny angles.
 
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When it kicks in at 85% open just run the water into a container for exactly 30 secs, measure this with a 1 or 2 liter milk bottle or whatever, X2, this gives the flowrate in LPM, post back.
Good idea,

So the two taps that don't work, the shower and kitchen taps both take 10 seconds to fill a litre jug. So 6 LPM

The bath and sink tap both take 6 seconds and does engage the boiler . So 10 LPM
 
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So, at 85% tap opening, it requires a flow rate of 6 LPM to fire the boiler?, the flow switch should switch in the boiler at well < 3LPM so unlikely to be that IMO since it was renewed, possibly sticking diverter valve?. Does this boiler have DHW preheat?, just wondering if there is a delay in the hot water coming through until the burner kicks in but obviously if cold water keeps flowing until the flowrate is increased then not the problem.
 
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So, at 85% tap opening, it requires a flow rate of 6 LPM to fire the boiler?, the flow switch should switch in the boiler at well < 3LPM so unlikely to be that IMO since it was renewed, possibly sticking diverter valve?. Does this boiler have DHW preheat?, just wondering if there is a delay in the hot water coming through until the burner kicks in but obviously if cold water keeps flowing until the flowrate is increased then not the problem.
Hi,

Yes it has preheat, I'll investigate the diverter valve in the morning. It's getting too late for technical issues!

I can definitely hear the water flow through the boiler when using the hot tap with or with out it fired. It's a strange one.

But thank you both for taking time in replying this evening.
 

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