Intermittent hot water from new boiler

[trotter]

Hi all,

I had a new boiler installed on Thursday, a Worcester Bosch / Greenstar 30i compact

All works well, heating is great... except our shower (which sits above the bath), which is sometimes OK (never really hot), sometimes hot/cold intermittently, and sometimes cold.

On the front panel you can see when a tap is calling for hot water - and the shower does not always trigger this. I turned the eco setting off and this did appear to somewhat make the boiler more sensitive and to fire up more easily when the shower was run.

We've not got great water pressure in the house but the previous boiler would fire even if taps were ran slowly. And the cold runs fast enough. We've descaled the shower head and the flow rate is, to me, decent.

Anybody got any thoughts - I want to do a bit of research before British Gas try to fob me off by saying it's an issue with our water pressure.

FWIW I don't recall the installer checking the pressure upstairs pre-installation. And it's no different now than it was with our much maligned previous bioler (a 10 year old ideal). Ironically I could have just insisted they fix the old one, they had heat exchanger, diverter valve and pump ready to fit them all. But it was breaking down every 6 months and just becoming a big headache.

Thanks all

 

[shambolic]

Eh, get your installer out to check fundamentals like crossed hot and cold pipes etc.
Then the manufacturer as its under warranty. Why get BG involved?

 

[trotter]

Eh, get your installer out to check fundamentals like crossed hot and cold pipes etc.
Then the manufacturer as its under warranty. Why get BG involved?

British Gas are the installer - I'm second guessing their response which will be that the water pressure into the house isn't strong enough. I called the chap who installed it an hour after he left and he suggested it was due to this, but it then worked, and I put it down to a teething issue. It's now proven to be an intermittent problem.

Pressure was fine for the previous boiler, plenty strong enough.

 

[shambolic]

They should be testing mains pressure to make sure it meets boilers minimum requirements.

 

[trotter]

They should be testing mains pressure to make sure it meets boilers minimum requirements.

Thanks. I don't recall them doing this.

I had a quote from an independent chap a while back and he used a tool to measure the flow rate of the bath taps. He said it was fine. Don't recall the British Gas people doing so. Should they have documented this?

Does it sound like a flow rate issue to you then?

Having lived in the property for 6 years the flow is never faster than it has been at times when the boiler hasn't fired.

 

[Daveydub]

Once hw flow rate exceeds 3 litre minute boiler should fire for hw. This would be the first thing to check. Now the shower. Perhaps a bit of dirt in filters after pipework disturbed?

 

[shambolic]

Flow rate is different from pressure though.

 

[Agile]

Hi all,

We've not got great water pressure in the house but the previous boiler would fire even if taps were ran slowly. And the cold runs fast enough. We've descaled the shower head and the flow rate is, to me, decent.

Thanks all

I have no idea what you think is decent.

As an engineer what I would like to know is the flow rate in litres per minute.

Tony

 

[gigz]

Take the shower head off and see if it gets any hotter, seen loads of examples where the shower head doesn't allow enough water through and the boiler modulates down. This could also be the reason for boiler not firing initially.
P.S. Any problems with the other taps ?

 

[trotter]

Thanks everyone, very much appreciate it.

Agile / Tony - in the context of my knowledge of the house, the shower is flowing as freely as it ever has - and hot water from the previous boiler always triggered when the shower ran. Appreciate a proper measurement is required. I'm going to attempt this tonight but my methods will be crude!

gigz - I took the shower head off the other day to clean it. While it was off I ran the water... and got no dice (or hot water). Occasionally the bathroom basin tap doesn't call hot water either. The bath tap and kitchen tap usually do (8 or 9 times out of 10) if fully open. They have failed to at times in the 4/5 days since installation.

This morning I took a shower, it was fine... 20 minutes later it wasn't calling hot water (as I found out when my wife was effing and jeffing!)


I should add water pressure to the house appears tremendously moody on all taps / outlets. Sometimes weak, sometimes strong.


I suppose, as much as a solution, what I'm looking to find out is what recourse I have with the installer. If they deem it's the mains pressure into the house that is the problem and there's nothing they can do - should they not have tested this before recommending this boiler?

It's especially infuriating that the previous boiler didn't have this issue and I could have had it fixed for free.

 

[Daveydub]

I should add water pressure to the house appears tremendously moody on all taps / outlets. Sometimes weak, sometimes strong.

So if they had tested during a "strong" time it would not have shown as a problem.
Is your external stop tap opened fully?
Ditto internal?
Does boiler fire at 3lpm?

 

[algas]

Sometimes the shower hose collapses internally

 

[Daveydub]

Occasionally the bathroom basin tap doesn't call hot water either. The bath tap and kitchen tap usually do (8 or 9 times out of 10) if fully open.

We seem to be moving away from the shower now. Could be a problem/mucky flow switch or barely open stop-tap, leaking main etc.etc. but

I suppose, as much as a solution, what I'm looking to find out is what recourse I have with the installer

this appears to be the focus of OP

 

[trotter]

Thanks everyone.

I measured the flow rate last night.

Bathroom sink just over 3l per minute when fully turned to hot (mixer tap) and 4l when cold.

Shower was just over 4l per minute.

Both called hot water.


Oh and yes recourse to the installer is my focus. I had a boiler that fired at all times. British gas suggested a new boiler as the old one kept breaking. Now it's 50-50 whether we can have a shower. Not good enough IMO

 

[shambolic]

Ideal Logic won't bring on HW if flow rate under 3 l/min your boiler may be similar.
As it uses a turbine spinning to bring it on.
Your old boiler Isar used a cold temperature thermistor that sensed the water entering the plate going cold and would come on at any flow rate.