New combi boiler - problems

DragonQ

I recently moved into a flat which had a brand new combi boiler fitted just before I moved in (band A condensing and all that malarkey). I've never had a combi boiler before and am having some issues with the hot water (haven't had a reason to try the heating yet):

1) It takes about 2 minutes of running the hot tap to get hot water. It gets a bit warm after 1.5 minutes and takes a further 30 seconds to get properly hot. This seems like a huge amount of time compared to a tank system but is this normal?

2) The hot tap pressure decreases after time. I turn the tap on so it's as high pressure as possible without splashing all over the worktop, then after about 20 seconds it's nearly turned into a dribble and I have to turn the tap up. I have to repeat this a few times until the water turns hot.

3) When the pressure is pretty low, the boiler seems to not realise that I'm using hot water, so it turns off. This is a problem because I only need the hot tap on low to get the temperature and water pressure I want for a shower, which means the water becomes cold 5 minutes after it first gets hot!

Are these things normal or is there a problem with the boiler, or maybe the whole hot water system? The only control I can see other than on/off is the temperature, which is set to 60 °C.

diywhynot

Make and model of boiler?

macman

What is the pressure gauge showing on the boiler?

sk240

It sounds like you have a flow problem somwhere, is your stopcock fully turned on?

As a test, run the tap for 1 min with a bucket collecting the water, and measure how much is in there.

You should hopefully have over 10l of water in the bucket.

If your stopcock is ok, it may be that a combi is unsuitable for your property, but this should have been checked before the combi was installed by the plumber.

DragonQ

diywhynot wrote: »

Make and model of boiler?

Can't remember but I can find out when I get home.

macman wrote: »

What is the pressure gauge showing on the boiler?

Within normal range (green bit).

sk240 wrote: »

It sounds like you have a flow problem somwhere, is your stopcock fully turned on?

Ah, when I moved in there was no water so I turned the stopcock on. Maybe I didn't open the tap fully. There was also a second tap that I couldn't budge - any idea what that could be?

sk240 wrote: »

As a test, run the tap for 1 min with a bucket collecting the water, and measure how much is in there.

You should hopefully have over 10l of water in the bucket.

Presumably you mean on full power? Might struggle not to get water everywhere.

DragonQ

I opened the stopcock to maximum but it didn't help much with the pressure problems with the kitchen tap. I did manage to have a shower yesterday without the hot water running cold though so maybe it has helped.

The boiler model is Promax Combi HE Plus A.

MoneyMate

I have the same problem with my Combi, Takes about 20 Secs for the water to get really hot, I think it has to heat up a long leg of copper pipe, if your tap has the more conventional rubber washers as they heat up they can swell in turn reducing water flow. :beer:

DragonQ

I'd take 20 seconds, that's a lot less than two minutes!

sk240

DragonQ wrote: »

Can't remember but I can find out when I get home.


Within normal range (green bit).


Ah, when I moved in there was no water so I turned the stopcock on. Maybe I didn't open the tap fully. There was also a second tap that I couldn't budge - any idea what that could be?


Presumably you mean on full power? Might struggle not to get water everywhere.

Yep run on full power, if you dont get 10l+ then a combi is not suitable for the property, either that of you have a faulty stopcock or a blockage somwhere

MoneyMate

DragonQ wrote: »

I'd take 20 seconds, that's a lot less than two minutes!

BUT if the washers are swelling then the flow will reduce, then the boiler reduces boiler output ? :beer:

diywhynot

DragonQ wrote: »

The boiler model is Promax Combi HE Plus A.

24, 28 or 33 kW?