Using Heating and Hot Water at the same time

ImranQ

Hi,
We have a normal boiler i.e Not combi. We recently had the pressure tank replaced in our system as the old one started leaking.

Since the replacement, I've seen two problems. The first is that there is a loud knock when the tap is turned on. I believe this is because there is air in the system?

Secondly, when the heating is on, the hot water doesn't seem to function efficently (or perhaps not at all). When the heating is turned off, the hot water seem to function normally. Any idea or reasons why this would happen? I'm pretty sure this never happened before the tank replacement and we could use both at the same time. I'm wondering if there is some issue as the plumber had to strip down all the components and piping around the tank to fit it.

Any help would be much appreciated. I'm going to get the issue resolved by the plumber who replaced the tank but want to find out the issue in case the plumber tries to fob me off.
Thanks,
iq

ProDave

When you say "hot water does not function properly" explain more what you mean.

As long as there is hot water in the tank, then turning the tap on will produce hot water at the tap regardless of what the boiler is doing, even if the boiler is off.

If you are saying that while the heating is on, then the boiler does not heat the hot water tank so when the hot water in the tank as been used up it does not re heat, then you have a problem with the controls or the motorised valves.  Call the installer back.

JJ_Egan

A knock can be a pipe banging . due to pressure to high or being moved .

Tap as in water tap should get rid of air in a few uses .

As above reads as motorized valve >> Can you see it and reset .

ImranQ

Thanks for the reply.

We have a Nest programmer and using the manual On/OFF.

If the Heating is ON, and the house has warmed up and we simultaneously turn the Hot Water ON in the Nest programmer the display says the Hot Water is ON as well as the Heating. But the water barely gets luke warm even after the Hot Water is on for 1/2hr or 1hr.

However if we turn the Heating OFF or if it was already ON and we turn the Heating OFF and then turn the Hot Water to ON, the water gets hot as expected.

Is this normal behaviour? I don't remember this happening before.

Verdigris

Installations vary, but usually the boiler only satisfies one load at a time. Mine always satisfies hot-water first, so the heating doesn't come on, first thing, for about 10 minutes, until the hot water tank is up to temperature.

ImranQ

JJ_Egan said:

A knock can be a pipe banging . due to pressure to high or being moved .

Tap as in water tap should get rid of air in a few uses .

As above reads as motorized valve >> Can you see it and reset .

Thanks for the reply.

We had the tank replaced in the middle of November and even though we have been running the taps, the knocking/banging sound is still coming. I've been trying to get the installer to come round to look at it but he seems to be 'mega busy' with other jobs now that he has been paid by me. Of course it is that time of the year anyway.

Sorry didn't understand what you mean by 'As above reads as motorized valve >> Can you see it and reset '.

ImranQ

Verdigris said:

Installations vary, but usually the boiler only satisfies one load at a time. Mine always satisfies hot-water first, so the heating doesn't come on, first thing, for about 10 minutes, until the hot water tank is up to temperature.

In our case with the heating on, the house is already hot so I assume the water is already hot. If we turn the hot water on, it is not working or working efficiently until we turn the heating off manually.

ProDave

Verdigris said:

Installations vary, but usually the boiler only satisfies one load at a time. Mine always satisfies hot-water first, so the heating doesn't come on, first thing, for about 10 minutes, until the hot water tank is up to temperature.

No a gas boiler is well capable of doing hot water AND heating at the same time.

If it worked with the old tank as you expect and does not work properly with the new tank, the installer has messed something up.  Plumbers are not usually electricians and it is amazing how many times they try and do something like that and mess it up.

ImranQ

ProDave said:

Verdigris said:

Installations vary, but usually the boiler only satisfies one load at a time. Mine always satisfies hot-water first, so the heating doesn't come on, first thing, for about 10 minutes, until the hot water tank is up to temperature.

No a gas boiler is well capable of doing hot water AND heating at the same time.

If it worked with the old tank as you expect and does not work properly with the new tank, the installer has messed something up.  Plumbers are not usually electricians and it is amazing how many times they try and do something like that and mess it up.

Many thanks. I'll get on to the Installer.

ImranQ

I spoke to the plumber who installed the tank and he claimed that he only installed the tank and that would have nothing to do with the heating/hot water issue even though he would have had to dismantle the hot water/heating switches etc.
FYI The boiler is in the kitchen and the tank and other piping/switches etc are in a different part of the house.

I'm totally puzzled as we haven't ever noticed this problem before the tank was installed. Any ideas what this issue could be due to?

Ectophile

It may come down to the controller, the 3 port valve and/or the thermostats (room and tank).

My central heating can be set to heating and water at the same time, but I don't bother, as the controller gets confused by two thermostats if one calls for heat and the other doesn't.