No hot water when central heating on

Benincasa

I am a complete novice when it comes to electrical and DIY issues so please forgive me if my question is ridiculously basic.

I moved into a new house 4 months ago that I had built earlier this year. We haven't had to have the central heating on until the recent cold snap.

The problem is that the hot water remains only very lukewarm when the heating is on. It is far too lukewarm to shave etc. Normally, when the heating is off and the boiler is on, the water gets quite hot. We had central heating installed in my home place about 15 years ago and it does not have this problem - both the radiators and the water will heat up nicely at the same time. I still owe retention money to the builder. Is there some easy task that the builder/plumber can do to rectify the situation? To my mind it is completely unacceptable.

I've also noticed a very loud humming noise from the hot press. It seems to be coming from a thing called a myson power extra. I've no idea what it does. I never noticed this humming before last week and it can even be heard from the other floors of the house. Surely this isn't normal?

Many thanks for your help!!

Mr Magnolia

Hi there,

I've no idea what the problem would be I'm afraid, I would recommend you call the builder and ask to get the plumber round to fully explain the workings of your system. You should certainly have hot water available to you if the heating in the house is on and running.

I'll move this to the Construction and Planning section of Home and Garden, you may get some help there. I'll also leave a re-direct in Electrical incase anyone has any ideas.

Mods, feel free to throw this back if you deem it appropriate

It sounds like you have an electric water heater.. is that correct and it's trying to heat the CH system.

Is there another boiler somwhere else that needs to be switched on (I know it sounds a silly question, but this is your first winter in the house).

Benincasa

Deleted User wrote: »

It sounds like you have an electric water heater.. is that correct and it's trying to heat the CH system.

Is there another boiler somwhere else that needs to be switched on (I know it sounds a silly question, but this is your first winter in the house).

Thank you for your reply.

I have a gas boiler. When I had the thermostats turned off there was no problem with the water. However, since turning them up, the radiators heat but there is barely any heat in the water. To my mind both the radiator and the water should heat simultaneously.

When the water wasn't heating I flicked on what looked like an immersion switch at the hot water tank (I was never told by the builder or plumber that they had installed an immersion system and it wasn't in the specs, and I only discovered it recently). This does heat the water. However, I have become aware of the loud humming noise from the myson extra gadget only since I first used the immersion. It still hums even when the immersion is turned off

Is the myson extra this.. if not post a picture of it someone here will recognise it.


if so it's a change over valve that switches hot water between the DHW & CH, in other words you have hot water or central heating but not both.

look at this site for more details, http://www.uk-plumbing.com/myson-2-port-power-extra-28mm-zone-valve-p-1431.html

Benincasa

Deleted User wrote: »

Is the myson extra this.. if not post a picture of it someone here will recognise it.


if so it's a change over valve that switches hot water between the DHW & CH, in other words you have hot water or central heating but not both.

look at this site for more details, http://www.uk-plumbing.com/myson-2-port-power-extra-28mm-zone-valve-p-1431.html

Thank you for your reply.

yes, that's pretty much what is installed at the hot water cylinder. Firstly, why is is humming and why did the humming on;y start within the last week?

Secondly, is it necessary? Is there some other kind of valve that can be installed that will give me hot water AND heating?

I can only guess as to how your system is wired, it may be that the central heating gets priority and all the hot water is pumped via the valve to radiators.

Then after the room thermostat reaches temperature the valve switches back (stops humming) and the hot water heats the cylinder.


Leave the heating/hot water on for a longer time and see if it switches over.




PS - Mods: should this be in DIY?

Benincasa

Deleted User wrote: »

I can only guess as to how your system is wired, it may be that the central heating gets priority and all the hot water is pumped via the valve to radiators.

Then after the room thermostat reaches temperature the valve switches back (stops humming) and the hot water heats the cylinder.


Leave the heating/hot water on for a longer time and see if it switches over.




PS - Mods: should this be in DIY?

Two quick issues on that - the valve hums constantly, even when the boiler is not switched on.

Secondly, to get hot water in the morning it would mean setting the boiler to run for a couple of hours - I have the boiler set for an hour at the moment and there is practically no hot water. Surely it is unacceptable to be faced with a choice between having heating on for hours to get decent hot water or else not having the heating on at all? Surely it can be rewired some other way?

Benincasa

Benincasa wrote: »

Surely it can be rewired some other way?

Yes it can be wired or controlled differently, the easiest thing to do would be to get the original installer back to check all is correct.

Then take it from there.

Mike2006

Looks like your electric valve is stuck almost closed.

There is a lever at the side of the valve that says Auto or Man.
Move the lever to the MAN position and click it into place so that it does not move back to Auto. This will force the valve open and you should now get hot water once your central heating is on.

Now for the technical bit:
There is an auxiliary contact on most of those valves and it is used to send the signal to the boiler to start up once the valve is open. If the valve is stuck, the boiler will not get this signal and your hot water will not heat up..

btw, you probably have 2 of these valves in the hot press, 1 for your hot water and the other for the central heating...

Hope this helps,

Mike.

Benincasa

Mike2006 wrote: »

Looks like your electric valve is stuck almost closed.

There is a lever at the side of the valve that says Auto or Man.
Move the lever to the MAN position and click it into place so that it does not move back to Auto. This will force the valve open and you should now get hot water once your central heating is on.

Now for the technical bit:
There is an auxiliary contact on most of those valves and it is used to send the signal to the boiler to start up once the valve is open. If the valve is stuck, the boiler will not get this signal and your hot water will not heat up..

btw, you probably have 2 of these valves in the hot press, 1 for your hot water and the other for the central heating...

Hope this helps,

Mike.

Thanks you for your help.

Yes, I have two of these valves although one of them is right in at the back of the hot water cylinder and I've no idea how anyone would actually reach it. I am getting the plumber back so I will get him to look at all of this.

Shazer01

Hi,
Just saw this post and was wondering if you could clarify something for me. My Myson extra is also making lots of noise when the hot water is switched on. I have a gas burner. It heats up the water and the heating at the same time or separately no problem. I have 2 of these mysons presumably to do the job separately if necessary. Should I be worried that it is making loads of noise when it starts to heat the water? The switch is on auto at the moment and dont know if I should get a plumber to look at it. Thanks if you reply.
regards..

muffler

Thread moved from Construction & Planning to the Plumbing & Heating forum