Problems with a boiler

[thorvald]

Hi,

I'm looking for some help and hopefully somebody will be able to advise here.

My parents live in the house from 1940s. The central heating installation is not that old I guess but it's something what I presume it's called and based on the single function boiler. There is a water tank in that installation. The programmer is set to heat the water twice a day.
Quite recently my parents noticed when the heating is on the radiators are getting hot as well. This should not be a case because a thermostat is turned off or set to be below 16 degrees whereas the temperature outside and inside is much higher. This wasn't a case before and when the programmer turned the heating on it only heated the water in the tank and radiators were still cool (desired in the summer of course) - not on winter though where the thermostat was set to something around 20 degrees.
I'm not sure where to start but I would probably get the thermostat replaced as it is probably broken but not sure if that might be a symptom of it.

What do you reckon ?

If that's the thermostat problem is this something what I can do myself ?

Thank you for your help in advance.

Regards.

 

[Burnerman]

Somewhere in your parents house (often close to the hot water cylinder) you'll find a motorised valve or two.....as the boiler heats the water, these valves direct the hot water to either the domestic hot water system, or the heating system or both.
These valves have an electric stepper motor inside, which turn the valves either off or on.....the chances are the motor has burnt out or the gear mechanism between the motor and valve stem has failed.
John

 

[thorvald]

I just realized that they mentioned it happened after the power outage they had so it's quite possible it damaged the valve.
Do I need to replace the whole valve ? Or only this motor bit ? Is it something I can do or I need a professional ?

Also if the valve will be fine does that mean the thermostat is broken ?

Thank you for your help John.

 

[Burnerman]

Its best to identify the type and make of the valve first.....a typical one is Toolstation 58520.
This is the valve power head, and it comes complete with a new motor and a length of cable.
With this type, the power head is held in place by two screws, under the outer cover. The water supply with this one is untouched so the fitting is simple.
Other valves (this one is a direct replacement for a Honeywell one) may have their own heads.
Motors are available separately (Toolstation 68222) if you want to fit one yourself, but its more complicated!
I would doubt if there is a thermostat problem here, but I'm only guessing obviously!
John

 

[thorvald]

Hi John,

I finally managed to go to my parents house and find out. There are two valves from what I have found and reading on the internet about the motor valves and their diagnostics there should be a lever which allows manual closing and opening the valve. If it's pulled it should close or open a valve... however this lever was quite loose what indicated a problem but... I was confused which valve does what so I took some pictures.

Can you tell me which valve is which and which one should be looked at ?

Thank you.

Regards.

View media item 64718View media item 64719 View media item 64720

 

[45yearsagasman]

The blue thingy is a mid position valve. If the rads are heating when only hot water is selected then almost likely to be a faulty valve. Thats a BG branded valve and the head can be removed from the body.(little black plastic push button on the side). Check that the exposed spindle is free to move. Chances are that the valve is passing inside and its better to replace the whole thing.

 

[thorvald]

Hi Pete,

Thank you for your reply.

I'm a bit confused when you say "If the rads are heating when only hot water is selected..." there is no place (or I don't know about any) where I could select that. I thought that it's the thermostat sets it on and off according to the temperature set on the knob.

Regarding the blue valve I have checked some are available on ebay but none of them are matching the numbers from mine (BGMVSP-23). There are some 2 port and 3 port valves. All Draytone valves. So I'm a bit confused on what I actually need to get :/.

Thank you for your help!