Hot water, but only just

[Littlespark]

Got a Worcester combi boiler that gets serviced every year through BG, but we are finding that the hot water is never that hot.

I think the water is passing through the boiler too fast and doesn't get a chance to heat properly.

Very noticeable on the bath, where we have to close the tap down quite a bit until the flow rate reduces coming out the tap.

Is there a way to reduce the flow rate as it goes through the boiler?

 

[JCplumb]

Never fitted one but I remember hearing about these a few years ago.
Combisave – Save water and money if you have a combi-boiler

 

[Aire]

Has it ever been hot or is the problem your describing always been present since install?

If it has then what you need to understand is depending on model, your boiler may only be capable of delivering as little as 10ltr/min of what you would class as hot water, or as much as 17ltr/min. If you have a lower kw rated combi you could quite easily be expecting to much from it.

If however, when installed, your hot water was great but is now poor. This could indicate a problem within your boiler. It's fairly easy to diagnose so long as your engineer is aware of the problem.

 

[Stu-B]

Do you have a pressure reducing valve on the incoming main cold water?

 

[ShaunCorbs]

What’s the model of the boiler ?

 

[Littlespark]

Bit of background. The house is 11 years old and was built with a Gloworm system boiler and hot water tank. 4 bedroom, 2 showers and a bath.
Because of really poor hot water pressure from the tank, we decided to have it changed to a combi, and free up the tank cupboard for storage.
Local Gas Safe plumber did the work, and we have had BG service it every year since.
I wouldn't say it was perfect from day 1, but certainly better than it was.

The boiler is a Worcester 37i (?) I think, without going out to the garage to check, and was told at installation it was the biggest they do.
I don't think there is a pressure reducing valve on the cold main.
There is an anti scald valve under the bath, but its set to be as hot as it can be.

 

[Rob Foster]

Never fitted one but I remember hearing about these a few years ago.
Combisave – Save water and money if you have a combi-boiler

I think installing a combi save would be really worth it. This would save you water and save fiddling round with flow rates. A 37i is well powerfull enough.
centralheatking

 

[Littlespark]

Combisave looks like a good bet.

Will Graham’s plumbing merchants have them, and roughly what cost to buy?

 

[Stu-B]

Will that cure it though?
I’ve never come across these but after a little googling I get the impression the combisave reduces the flow until the dhw temp reaches 45C then opens fully. This way it saves water on the initial draw off, but after that you’re back to where you were to start with surely? Full flow which isnt getting hot enough, then I’m assuming the combisave willjust modulate the flow up and down with the temp? Or did I miss something here??
Thats no fix, you need to be looking at what’s coming in to the boiler instead of some gimmick. Get a proper plumber in to test your water flow rate, pressure and the blend valve under the bath, then adjust accordingly.

 

[Rob Foster]

Will that cure it though?
I’ve never come across these but after a little googling I get the impression the combisave reduces the flow until the dhw temp reaches 45C then opens fully. This way it saves water on the initial draw off, but after that you’re back to where you were to start with surely? Full flow which isnt getting hot enough, then I’m assuming the combisave willjust modulate the flow up and down with the temp? Or did I miss something here??
Thats no fix, you need to be looking at what’s coming in to the boiler instead of some gimmick. Get a proper plumber in to test your water flow rate, pressure and the blend valve under the bath, then adjust accordingly.

Do both and you will never look back. chking

 

[Millsy 82]

I think installing a combi save would be really worth it. This would save you water and save fiddling round with flow rates. A 37i is well powerfull enough.
centralheatking

Honestly how much water do they save though? Modern combos fire up and ramp up to max within a matter of seconds the plate starts getting hot within 10 seconds so with a 30kw combi probably save a litre if you open the tap fully straight away. Most of the water people waste is what's in the pipe.

 

[Littlespark]

Did a little research, and I can get the combisave gizmo for 50 quid. Worth a shot.
I understand how it works, and for filling a bath, it seems sensible... but what happens with the showers? Will they fluctuate in pressure with the combisave in use?

 

[Rob Foster]

Did a little research, and I can get the combisave gizmo for 50 quid. Worth a shot.
I understand how it works, and for filling a bath, it seems sensible... but what happens with the showers? Will they fluctuate in pressure with the combisave in use?

Have a look at shower power booster from Alan Wright ..he was on dragons den, nice man very clever unit. centralheatking

 

[Rob Foster]

Did a little research, and I can get the combisave gizmo for 50 quid. Worth a shot.
I understand how it works, and for filling a bath, it seems sensible... but what happens with the showers? Will they fluctuate in pressure with the combisave in use?

Ring teddington systems in St. Austell technical advice

 

[Darren Jackson]

How old is your boiler?

 

[Gasmk1]

Has BG looked at it can't see it just being too fast a flow there must be another problem if water not hot enough eg:- heat DHW heat ex clogged up or sensors out of wack

 

[Rob Foster]

Has BG looked at it can't see it just being too fast a flow there must be another problem if water not hot enough eg:- heat DHW heat ex clogged up or sensors out of wack

out of wack....thats a smashing diagnosis I am going to adopt it
if thats ok ...cheers centralheatking

 

[Millsy 82]

Has BG looked at it can't see it just being too fast a flow there must be another problem if water not hot enough eg:- heat DHW heat ex clogged up or sensors out of wack

If bg thought there was even the slightest bit of muck in there they would be charging them £1000+ for a power flush.

 

[Gasmk1]

If bg thought there was even the slightest bit of muck in there they would be charging them £1000+ for a power flush.

But if it was better than now when first installed then it's not just flow rate so there must be other contributing factors

 

[Millsy 82]

But if it was better than now when first installed then it's not just flow rate so there must be other contributing factors

Don't disagree but you've got to admit they are very quick to blame sludge and will soon push their very expensive flush

 

[Aire]

Don't disagree but you've got to admit they are very quick to blame sludge and will soon push their very expensive flush

Agree on that one, I had one customer who had been told by BG her system was full of sludge and needed a powerflush. Stupid quote for the work when all that was needed was a new ball valve in the loft as it had seized and system had dried up.

 

[Welder]

Agree on that one, I had one customer who had been told by BG her system was full of sludge and needed a powerflush. Stupid quote for the work when all that was needed was a new ball valve in the loft as it had seized and system had dried up.

That's bl00dy appalling

 

[Rob Foster]

That's bl00dy appalling

bg staff are largely sales driven NOT problem solvers. there is little profit in their servicing business its the add ons that they can sell that keep,that business alive. and of course the radicals but you need experienced staff allocated enough time to do radical jobs properly
Rob Foster
aka centralheatking

 

[Littlespark]

I’ve been out to check. Boiler is a Worcester 30CDi, not 37 as I first thought.

 

[Aire]

I’ve been out to check. Boiler is a Worcester 30CDi, not 37 as I first thought.

Probably a little underpowered for your usage, but as previously mentioned, there may also be issues within your boiler.