Any idea what this is?

[SJRSJR]

It's under the floorboards, attached to a central heating water pipe. As you can see a cable leads to a junction box and the other cable going out of the top of the picture isn't attached to anything, although directly above is an old CH thermostat. Thanks.

View media item 76232

 

[Taylortwocities]

It is a valve.

It will open and close and let water through to wherever it goes to. May be a heating zone controlled by a thermostat.

 

[SJRSJR]

Thanks. Does it need power? It doesn't seem to have any!

 

[JohnW2]

Thanks. Does it need power? It doesn't seem to have any!

As TTC has said, it will be controlled by a CH controller and/or a thermostat. If it's a 'zone valve' and that zone is not selected (and CH switched on!) and/or a thermostat has switched it off, then there would be no power to the valve.

Try switching on your CH, selecting all zones (if there are more than one) and turning all thermostats up to maximum temp - then see if there is any power to the valve.

Kind Regards, John

 

[Taylortwocities]

Take the cover off that junction box that the wire goes in to.
What connects to the cable from the valve, is it the white wire, or the black flex?
Its hard to say from that picture.

It may just be old and redundant, the pipes may also not be used any more.
Do they get warm, ever?

 

[AndyPRK]

Sometimes there is an override lever on the valve to let water through.
Don't mess with it.

 

[SJRSJR]

Thanks for the replies. Can't see any switch but it is attached to a hot pipe. When we moved in there was a brand new stand alone boiler not connected to any thermostat. Can we forget about this and use a wireless thermostat?

Here's the junction box. The cable out bottom goes to the valve and the one out right isn't connected.

View media item 76234 [/img]

 

[JohnW2]

Here's the junction box. The cable out bottom goes to the valve and the one out right isn't connected.

Do you mean that the cable on the right goes nowhere? If so, as has been suggested, provided that your CH is working satisfactorily, I would just forget about it, and assume that either the pipe in question is no longer in use or that the valve has been manually 'locked' into the 'open' position. If the cable on the right just has an unconnected end, you could remove it, for neatness.

Kind Regards, John

 

[SJRSJR]

Thanks John, that's what I'll do.

 

[xr4x4]

The valve could of been set to be manually open.

 

[JohnW2]

The valve could of been set to be manually open.

Indeed so ....

Sometimes there is an override lever on the valve to let water through.

... or that the valve has been manually 'locked' into the 'open' position.

Kind Regards, John

 

[ericmark]

As said could be redundant. The bypass lever would often only half open the valve only really there to bleed the system. Often there is a micro switch inside the valve and the thermostat opens the valve and the valve then demands heat from the boiler. They were common with older systems but today the zone valve is part of the thermostatic radiator valve (TRV) and Wifi connected to controller as the modern boiler is condensating and instead of on/off it varies in output.

The variation in boiler output is controlled by the return water temperature and the TRV is an integral part of the system. The better boilers have anti-cycling software and this monitors after a set time from switch on (longer enough to warm pipes) if the return water is hot or cold. If hot it switches off and extends the period before switching on again and if cold stays on and shortens the time between off and retry.

In other words the TRV does the room temperature settings not a room thermostat the TRV can be connected to a room thermostat but not the boiler. The boiler does have the option for a out side thermostat to stop it firing up on warm days and a timer but today we control the temperature room by room with the TRV not house as a whole.

Although TRV can have WiFi heads and be connected to a central processing unit so for example master bedroom heat does not turn on until 10pm but living room switches between low temperature (17 deg C) to sitting temperature (20 deg C) as 6pm and then down to holding temperature (12 deg C) over night.

This is a problem with non electrical TRV they have just one temperature where with a wired electrical thermostat it does not just switch off but changes between set temperature range. Wired these thermostats are cheap but radio linked they become far more expensive and most wireless are simple on off with no time setting.

Unfortunately many firms fitting central heating do not train their employees on how the modern system works and they as a result go by old rules like leaving one radiator without a TRV which messes up the anti cycle software in the boiler.

In a correctly set up system with the lock shield valves trimmed correctly with by-pass valve near the boiler and TRV on all radiators all that is required is a time clock with a over ride thermostat to stop freezing.

However with my mothers the fitters left are the lock shield valves wide open and while the heating is not turned off this works OK each TRV will control how much water goes to each room. However if turned off and allowed to cool on re-start the easiest route will have all the hot water and will allow the still hot water to return to the boiler so turning down the boiler. The net result is the rooms are heated one at a time instead of all together giving a very much extended time from switch on to all rooms being at TRV set temperature. Unlike the old system where if hot water was returned if just boosted the head and sent it around again the new system has to have return water under a set temperature for the condensate to form. This means very careful setting of lock shield valves to ensure fast warm up over the whole house.

Fitting a thermostat to boiler rather than to TRV can mess the whole system up and unless you understand what you are doing it could make things worse not better.

Houses have different designs and what may work with one house may be a complete failure with another. Our first house had hot air central heating air sucked in from living room and heated and blown to all rooms in the house. With this a single thermostat is all that is required. Common in USA and using smart phones to set temperature and on times is popular as it only has to control one device. In this country with hot water system every room has it's own device so it would need far more to control from the phone with a WiFi TRV in every room and the cost of remote control would be far higher.

I know with my sons house setting the intruder alarm auto reduces the heat in down stairs rooms and bedrooms only heated 1/2 hour before they retire all from a central controller. However the hysteresis is a problem and at the moment we are considering using Arduino units and building our own controller to counter the hysteresis problem. Radiator type will affect the hysteresis they Myson are very good with very little over shoot where as under floor heating is very bad with a huge over shoot.

Maybe we should return to a central wood fire in the house heating all rooms? At the moment building the Arduino to keep my beer at a consent temperature once cracked with beer then house is next.