Combi Boiler Heating

russeddy

Hi,
I've got a fairly new combi boiler but recently the hot water supply is tempremental, if the tap is fully open the water temperature decreases, but if the tap is only partially open the water temp is fine.
Any ideas?

nickcc

All the combi's i've had always work the same way, if the flow is too fast the water doesn't get time to heat up to the correct temperature. We also get problems with the changeover valve when the central heating is on and the demand for hot water is required, takes ages for the hot water to come through as the changeover valve is slow to operate.

Klug

Hi, same as above really. The boiler heats the water as it is demanded. If you open the tap fully, then it hasn't got time to heat it at that volume. If you open it say
halfway, then it has better chance of keeping up with the flow. Our problem is that if someone is using the shower, it prioritises that and if you run the kitchen sink as
well, it can't do both, either the kitchen water is cold or the person in the shower gets a chill!! lol.

russeddy

whats strange is the hot water has worked fine with the tap fully open until recently.
i'm hoping its not a fault part in the boiler!!!

Ectophile

Remember that the incoming mains water is colder in winter than in summer. A boiler that can give lots of hot water in summer may struggle to get it hot enough in the winter.

Because the pipes are buries underground, it may take a while for the water to reach full chilliness as winter sets in.

keystone

russeddy wrote: »

Hi,
I've got a fairly new combi boiler but recently the hot water supply is tempremental, if the tap is fully open the water temperature decreases, but if the tap is only partially open the water temp is fine.
Any ideas?

How new is fairly? Is it and its installation still under warranty? If so and as its a recent fault then you should be getting the installer back to it and no gerfingerpoken by you in the meantime.

Cheers

keystone

Ectophile wrote: »

Remember that the incoming mains water is colder in winter than in summer.

But not that much.

Because the pipes are buries underground, it may take a while for the water to reach full chilliness as winter sets in.

Actually you'd be surprised how constant the temperature the ground is all year round even a couple of feet down.

Cheers

nickcc

We also find that the hot water takes longer to heat if there is demand from the central heating (change over valve fault) With our boiler hot water demand takes precedence over central heating demand but with newer boilers could the demand be shared which would result in the hot water taking longer to heat when the heating is on ?