Thermostat and central heating

[functor]

New property..

I recently had an incident where a family member "broke" the thermostat by using a wall steamer under it. I got a new one, connected it, the lights all turn on ok - but the central heating bodies don't get warm.

The boiler does make noise as soon as I switch the isolator on, but I can't tell if it's doing anything else when the relay on the new thermostat is on or off.

I also removed 3 heating bodies (closing the valves they were connected to)

Now, three things could be wrong here

1. The new thermostat is wired wrong

2. The electrics on the boiler side blew some kind of fuse? (Although I can see power coming through the live wire)

3. The central heating bodies run in series, and when I remove 1 the rest don't work??

Any other explanation? Do I get a plumber or an electrician?

Some information:
Old thermostat: Honeywell T6360B
New thermostat: Honeywell CM927

Connected:
1 -> L (brown)
2 -> N (blue)
3 -> B (red) ?

Heater is a Baxi, will get model when I get home.

I also have a Drayton Lifestyle LPx22 programmer

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[D_Hailsham]

New property.

Presumably you mean you have just moved in, not that it is a new-build property.

How old is the house and how old is the heating system?

I also removed 3 heating bodies

They are called radiators or, more accurately, emitters.

Now, three things could be wrong here

1. The new thermostat is wired wrong

That's definitely true.

Some information:
Old thermostat: Honeywell T6360B
New thermostat: Honeywell CM927

Connected:
1 -> L (brown)
2 -> N (blue)
3 -> B (red)?

Where does the CM927 get the supply to L and N from? Is it the Drayton programmer? If so, you need to set the Drayton to CH always on.

Have you inserted a link between L and A in the CM927? If not, you need to.

 

[functor]

Yes, I just moved in.

The house is 1930s, the heating system is probably newer than that - the owners never specified.

I know that the Drayton needs to be CH always on, it has always been

Let's see if I have this down correctly

What was on 1 (brown) needs to go to L1, this is "Live"

What was on 2 (blue) needs to go to N, this is "Neutral"

What was on 3 (red) is "Switched Live" and goes to B

I guess what you are referring to is:

http://www.honeywell.cz/home/Odb.clanky/DT92A.pdf

Just putting a wire to connect L2 to A?

 

[D_Hailsham]

The house is 1930s, the heating system is probably newer than that - the owners never specified.

If it's a very old system, it might be a one-pipe system. In which case removing a rad could break the circuit.

What was on 1 (brown) needs to go to L1, this is "Live"

What was on 2 (blue) needs to go to N, this is "Neutral"

What was on 3 (red) is "Switched Live" and goes to B

That's correct.

Just putting a wire to connect L1 to A?

The thermostat's switch terminals are A and B. At the moment A is not connected to anything. It need connecting to a 240V supply and the obvious place is terminal L1. (A = 1 on the old stat; B = 3.)

 

[functor]

Here is the wiring diagram for the receiver end on a typical boiler:

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Why not connect L directly to A?

EDIT: To answer my own question.. It could be because it needs power to function? (It has an LED and is a receiver after all... ) and A-B is just a relay.

 

[functor]

The house is 1930s, the heating system is probably newer than that - the owners never specified.

If it's a very old system, it might be a one-pipe system. In which case removing a rad could break the circuit.

That's what I was afraid of - other than taking out the flooring, any way to check? It seems like a lot of the piping goes into the loft.

 

[D_Hailsham]

Why not connect L directly to A?

L or L1, it doesn't matter which; they both will supply 240V to terminal A.

Can you post some pics of the rads and the associated pipework?

 

[functor]

L or L1, it doesn't matter which; they both will supply 240V to terminal A.

Sorry, what I meant was, in the wiring diagram it says to connect "Live" to Pin 2 (L) and then for me to manually connect Pin 3 (L as well) to A using a bit of wire. I was wondering why not connect "Live" directly to "A", but then I realised the "L" is to power the device and the "A" is to close the circuit.

Can you post some pics of the rads and the associated pipework?

Will do, as soon as I get home.

 

[functor]

Here are some pictures:

New wiring of BDR91:

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Boiler pictures:

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Rad pictures:

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[functor]

Even when connecting L to A, it still does the same thing. Whether the relay is open or closed, the boiler makes the same sound and I do not hear any water flowing through it. Do you think the rads are so old they are connected in series?

P.S. I can't put the rads back yet because some of the valves were completely broken / grinded in / wouldn't even close. And in that respect, how easy is it to replace the valves without getting water everywhere?

 

[functor]

OK, Central Heating works now, however - since always, the boiler seems to switch on and off "Burner On" even though CH and HW is OFF. It isn't always on, it alternates. Is this normal? I am investigating if the heaters are still being heated even though I have CH to OFF...

 

[D_Hailsham]

New wiring of BDR91:

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But there is no link between L and A!!

 

[functor]

New wiring of BDR91:

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But there is no link between L and A!!

There is now, that was the original picture

 

[D_Hailsham]

OK, Central Heating works now, however - since always, the boiler seems to switch on and off "Burner On" even though CH and HW is OFF. It isn't always on, it alternates. Is this normal? I am investigating if the heaters are still being heated even though I have CH to OFF...

You have a wiring error somewhere.

In your second pic (the HW cylinder in the loft) there is a motorized valve to the right of the cylinder. (It's the grey box near the floor). Is that the only valve you have and does it look like this (three pipes connected)?

View media item 5946
If so the valve may be faulty.

 

[functor]

Could the short circuit at the thermostat level have broken the motorized valve, or is this problem most likely from before?