Changed a radiator, now no CH? (Fixed)

Peteski · 21 Mar 2008

Hi,
I removed an old radiator (was tiling my cousin's bathroom) and replaced it with a new one. Now there's no central heating.

Boiler is a Baxi (no model details on the front)
Pump is a Grundfos one (gets hot to touch)
also has a Honeywell sundial Y plan 3 position diverter valve

When the water heating is selected the boiler fires up. When just the CH is selected the boiler doesn't fire up (just the pilot light on).

The water in the upstairs radiators gets luke warm to touch when the water is being heated but otherwise nothing.

I must admit to not knowing what to do now.

I have bled all the radiators to remove the air, I assume this was a success as water comes out of each radiator bleed valve now.

Any suggestions would be appreciated.

TIA

EDIT: I went over yesterday to test the white wire as suggested to see if I could isolate the problem. Before I did that I undid the big shiny round screw on the pump and some water came out - only enough to wet about a handspan on the floor then I put it back in.

Next I took the case off the 3 way valve to see if I could see a switch - couldn't recognise anything so I then took the front of the wiring box and got my cousin to switch the thermostat up and down twice so I could see if a signal was sent.

It was and now the CH works. Don't know why but we're both happy

Thanks for the help guys.

waterworks · 21 Mar 2008

Most likely a problem with the motorised valve, on one end is a lever is this lever moving when you select heating should go slack, if not the synchron motor has probably gone.
Have you got a room thermostat and is it turned up?.

Peteski · 21 Mar 2008

The diverter valve is over to the left normally. If I move it to the right manually and fiddle with the thermostat it moves back to the left by itself.

The main CH thermostat is turned all the way up to 30. The one on the new radiator is set to 5.

Peteski · 22 Mar 2008

Could this be an air blockage vcausing the problem or woud the boiler fire up for the CH even if it had a blockage?

seco services · 22 Mar 2008

it should still fire up even if its airlock or blockage the boiler won't know that.
sounds like the mot valve is not making the micro switch inside.

Agile · 22 Mar 2008

If the pump is too hot to touch that indicates there is no water flow.

May need air bleeding from pump or an airlock. See FAQ topic for advice.

The boiler itself should still be firing up and getting hot! Have you felt it to see if its been on?

Tony

Bluejohn · 22 Mar 2008

For what it is worth, my problem has just been fixed having done the same type of change of radiator thing, by running the pump with the plug out. Although water was coming out when bleeding, it seems not to have been running right. I isolated either side of the pump, took the plug out, started the pump, stopped it, opened valves and started again, and away it went. Then put plug back in. Don't take this advice as being anything other than something I was told to do by Scatman John- I haven't a clue, just sounds the same as my problem.

Peteski · 22 Mar 2008

seco services said:
it should still fire up even if its airlock or blockage the boiler won't know that.
sounds like the mot valve is not making the micro switch inside.

Is there any way to check if it is a non switching issue? I'm assuming the slider on it that can go from the left (where it says Auto) to the middle (no writing) to the right (where it says Man something) will have no bearing if a switch inside is not working.

Peteski · 22 Mar 2008

Agile said:
If the pump is too hot to touch that indicates there is no water flow.

May need air bleeding from pump or an airlock. See FAQ topic for advice.

The boiler itself should still be firing up and getting hot! Have you felt it to see if its been on?

Tony

The boiler won't fire up at all with just the CH on, even after draining the system. Switch on the HW and bingo it fires up fine with a lovely clean blue flame.

The pump temperature is like a hot plate in a carvery. I find it hot to touch but everyone else carries them fine. I figure having hot water go through it from the boiler to the tank would heat it anyway so that symptom I'm thinking is probably a red herring on my part.

seco services · 22 Mar 2008

moving the lever manual will open the valve but dosen't allows touch the microswitch.
remove the lid and check inside.
or find your wiring centre box and remove cover check if you have power at the white wire with a multi meter etc.
turn programmer on heating and stat up to max.

Peteski · 22 Mar 2008

Bluejohn said:
For what it is worth, my problem has just been fixed having done the same type of change of radiator thing, by running the pump with the plug out. Although water was coming out when bleeding, it seems not to have been running right. I isolated either side of the pump, took the plug out, started the pump, stopped it, opened valves and started again, and away it went. Then put plug back in. Don't take this advice as being anything other than something I was told to do by Scatman John- I haven't a clue, just sounds the same as my problem.

I'll be over there again either this afternoon or tomorrow so will try this if for no other reason than I'm stuck lol. The boiler doesn't fire up at all with just the CH on which is different to your issue but as I say I'm willing to try anything.

I didn't think a pump would work without it being plugged in.

Am I right in thinking these are the steps to follow:

1. Isolate the pump, which in this case if memory serves will require draining the system as there aren't any valves immediately before or after the pump so I wil have to remove it.
2. Remove the plug from the socket.
3. Start pump (not sure how to do this so any advice would be appreciated).
4. Stop pump.
5. Open valves (is this valves in the pump?)
6. Start pump again.
7. Plug pump back in.

seco services · 22 Mar 2008

the pump won't have a plug it will be wired into the wiring box with all the mot valve,stat,boiler etc

Peteski · 25 Mar 2008

I went over yesterday to test the white wire as suggested to see if I could isolate the problem. Before I did that I undid the big shiny round screw on the pump and some water came out - only enough to wet about a handspan on the floor then I put it back in.

Next I took the case off the 3 way valve to see if I could see a switch - couldn't recognise anything so I then took the front of the wiring box and got my cousin to switch the thermostat up and down twice so I could see if a signal was sent.

It was and now the CH works. Don't know why but we're both happy

Thanks for the help guys.

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Changed a radiator, now no CH? (Fixed)

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