Greenstar 24i junior Low hot water pressure

sampras · 4 Dec 2008

Just had a a Greenstar 24i junior combi-boiler system replacing a conventional boiler system.

House has 3 bedrooms and 1 bathroom, with a kitchen sink (hot & cold tap), bathroom sink (hot & cold tap) and bath (hot & cold tap).

Heating is fine, however hot water pressure is poor. If downstairs hot tap is on bathroom sink hot tap and bath hot tap has no flow whatsoever.

Worcester have been out twice and confirmed the boiler is functioning normally and the hot water flow out of the boiler is correct.

The plumber who installed the boiler has removed the flow restrictor and this improved the flow considerably to what you would expect, he then put the restrictor back in and called Worcester out to check there was no fault with the restrictor. Worcester attended site with the plumber who installed in attendance and confirmed the boiler was working, when the plumber suggested removing the flow restrictor the worcester maintenance engineer would not entertain it as the boiler was functioning correctly.

The water pressure into the house is fine. Any ideas on what the problem?

Would the warranty of the boiler be affected it the flow restrictor was removed?

Why should you need to remove this part for the boiler to function?

Rob · 4 Dec 2008

The restrictor is there for a reason. If you remove it you may get plenty of water out the tap but it won't get hot. A 24kW boiler might only do 8-9 ltrs to a reasonable temperature.

Combis arent designed to do two taps anyway but if you can live with the restrictor removed i cant see it being a warranty problem.

gremlin16 · 4 Dec 2008

Greenstar 24i junior

It only a basic baby boiler. To small for your hot water demand.

It will only provide you with a max of 9lt/min @40degree rise.

The installer should have recomended at least a 30Kw or better still a 35Kw boiler.

sampras · 4 Dec 2008

gremlin16 said:
Greenstar 24i junior

Click to expand...

It only a basic baby boiler. To small for your hot water demand.

It will only provide you with a max of 9lt/min @40degree rise.

The installer should have recomended at least a 30Kw or better still a 35Kw boiler.

Thanks you both for your prompt responses. That has been my worry since I discovered the problem.

I understand that when 2 taps are turned on there will be reduced pressure but I wouldn't expect there to be no flow at all. I have friends with the same model boiler, albeit an earlier version, and slightly larger houses without the same problems I'm having.

Worcester engineer confirmed flow rate is ok but would only do it with one tap running. Is there anything else I can do?

gavinda · 4 Dec 2008

check your mains stopcock is fully open as this wont help matters. my greenstar 35 only just slows down when anothe tap or apliance is on, but i have got 22mm right up to the backplate

.

bengasman · 4 Dec 2008

flow and pressure are, although related, 2 different things. you have lack of flow, not lack of pressure.
installer should have recommended spending a couple of hundred quid more and get a 37 cdi which has far more capacity, better controls and better quality. i can never understand why they install these baby things as a proper one will only up the price of the whole job about 10%; much better value for money

gavinda · 4 Dec 2008

but a half open stopcock would reduce both

bengasman · 4 Dec 2008

gavinda said:
but a half open stopcock would reduce both

i tend to measure water pressure with the taps closed

gremlin16 · 4 Dec 2008

i can never understand why they install these baby things

These clowns are the ones that are undercutting us.

Been out to similar problem last week, 3 beds 2 bathrooms 1 bath and one with shower.

Customer complaining that bath was slow filling and shower pressure drops.

Explained that a WB 25Si was to small for hot water demand

Her installer had worked out heat loss for house and that a 25Kw was large enough.

When I explained that was not the case she accused me of being a scaremonger, and that her installer came highly recommended and his price was very cheap.

I politely told her to get in touch with the installer, then she flipped and said he does not answer the phone and that she had heard that our sort were to expensive and also out to make more £££££ than she paid.

Exit front door and switched off phone.

gavinda · 4 Dec 2008

see the sig above yours

bengasman · 4 Dec 2008

They are not undercutting me. They are welcome to all those people who get 17 quotes and go with the cheapest.
Not exactly a new principle that when you pay cheap, you get cheap.

sampras · 4 Dec 2008

gavinda said:
see the sig above yours

Thanks for the feedback

The stopcock can be opened fully. Hot water symptoms are the same.

Its only a terraced house with only 1 bathroom with a bath and basin (no shower) and a kitchen sink.

Fortunately my plumber is still answering my calls and actively attempting to fix the problem. Although it may appear so I did not attempt to do this on the cheap. I would've paid for whatever boiler was specified. I'm just looking for extra advice any of which is helpful.

1.
The pipes go up from the boiler and rather than straight to the bathroom which is on the floor above and about 7/8 metres to the left they go across the landing to where the old cylinder was and back to the bathroom, at least doubling the amount of piping. Maybe an obvious question but would this make a difference?

2.
When turning on the hot water tap downstairs for the first second it spits the water out at high pressure and then settles down to an even flow. Is this correct?

3.
Is my only option a bigger boiler when I have friends/work colleagues with same model boiler in bigger houses.

bengasman · 4 Dec 2008

length of pipe has little influence in this case.

the worcester engineer can safely be assumed to know his stuff, so if he says the boiler works to spec, there is nothing left to be improved.

you can remove the restrictor, which will increase the flow, but it will also make the water significantly less hot when you turn the tap fully open.
product of volume and temperature can not be increased.

sad but true, you will either have to live with it, or fork out another 1500 or so to get a significantly bigger model.

gavinda · 4 Dec 2008

run yer tap slower gfor more heat. but if you measure flow from the taps you'll see that 8-9 lpm is not a great deal.

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Greenstar 24i junior Low hot water pressure

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