Sidetracked into 3-way valve solution?

[Sawkins]

Hello again all...

I came on here intending to post the 3-way valve question below, but got sidetracked into reading this thread about how the A side of the valve is supposed to go to the radiators and the B side is supposed to go to the cylinder.

I checked mine and it's the other way round. And that might explain why the room thermostat can turn the heating on in the middle of the day when the controller is on 'H twice, W once', as well as the chronic 'lukewarm hot water' problem.

Before I get someone in to replace it for me, can I ask please, is it really that simple? could there be any sensible reason for installing the valve the other way round?



(This was the original question btw)

I'm trying to work out whether my 3-way valve is stuck in the 'both A and B' position.

Both output pipes are hot, but I wondered if that could just be because the heat is being conducted along the pipe from the open side to the closed side?

If I had any spare copper pipe I'd get the kettle and experiment. As I haven't, could I draw on your pipe heat conduction experience please?​

 

[ScottishGasMan]

You are correct in saying B=Hot water and A=Heating.

99.99% of installs are fitted this way, there are a very small number of reasons why an installer would "Choose" to do it the other way round, and someone doing that would get the wiring correct.

So chances are yours is back to front. BUT, The fact that the room stat can operate the valve during the Day when the Hot water is on at clock suggests strongly that it has also been wired wrong, as the room stat should have zero effect when its not being powered by the Heating setting on the clock. This would suggest that the hot water on the clock is linked to the room stat.

If I were you I would be looking into tracing the wires and rewiring the lot from scratch (not physically removng the cabling and renewing, but undoing the connections in the junction box and redoing it correctly per a wiring diagram for a Y-plan system)

However that does require a degree of electrical competency and a lot of electrical saftey so if you are in doubt get somone in, if you have a multi meter and know how to use it get searching for a Y-plan diagram

heres a good place to start

http://www.flameport.com/electric/central_heating/heating_wiring_Y_plan.cs4

 

[D_Hailsham]

the A side of the valve is supposed to go to the radiators and the B side is supposed to go to the cylinder.

That is true for 99.99% of installations, but there are cases where the boiler manufacturer recommends fitting the valve the other way round. One example of this is the Remeha (Baxi) Avanta when weather compensation is used.

Can you provide the following info about your system:

Boiler make & model
Programmer/Thermostat make and model

 

[ianmcd]

Ha Ha your post reminds me of when I was an apprentice and I was told that B was for Bath and A was for arse I still remember that when I fit them

 

[Sawkins]

I've got intrigued by this now, so this afternoon I tested all the combinations of both thermostats, the time period and the controller setting. I found that the room thermostat could start the heating in 'H off W twice' mode during the twice period, and in 'H twice W once' mode during the once period. I wondered if whoever installed the valve was trying to reverse the effect by doing the wiring backwards too, but gave up halfway through.

It was very educational doing this test btw, I could see the valve motor gamely trying to move back and forth according to whether the room or cylinder thermostats were on.

the A side of the valve is supposed to go to the radiators and the B side is supposed to go to the cylinder.

That is true for 99.99% of installations, but there are cases where the boiler manufacturer recommends fitting the valve the other way round. One example of this is the Remeha (Baxi) Avanta when weather compensation is used.

Can you provide the following info about your system:

Boiler make & model
Programmer/Thermostat make and model

Stelrad Ideal RS60
Danfoss 3060/and both thermostats are Honeywell ones, model unspecified

 

[Dan Robinson]

Tricky to think back and imagine what the installer had in mind if anything.

As has been said, if it was intended, then the installer was aiming for hot water priority. However, it sounds unlikely in your case.

 

[Nige F]

Imagine....... a Chaffoteu (sp) boiler fitted by a young plumber (way before corgi and GS) and with the engineer houseowner wired with a Y plan. All works fine for 20+ years. Boiler is renewed by GS fitter because of regs, all certified and signed off. The engineer still lives there and finds that after the install it all works in a bizarre fashion, so calls the (now old) plumber to have a look - they find the fitter/electrician has removed the original 2 channel programmer and wired in a new 1 channel one . Did I cuz I was that plumber.