No Power to Central Heating Pump

pigeon1974 · 11 Nov 2006

Hi

Wondering if anyone can help? My radiators are hot upstairs but cold downstairs. The pump appears not to be working. After checking the power before replacing the pump it has none. Can I wire the pump directly to the mains and switch it on and off manually?

Thanks for your help.

breezer · 11 Nov 2006

well if it is not working since you changed it would it not be a good idea to follow the pump cable back and see is it still connected?

pigeon1974 · 12 Nov 2006

I've not actually changed the pump. I thought it wise to quickly check the electrics before doing any plumbing. Turns out the live cable is not live when you turn on the central heating or turn the thermostat up.

Alfredo · 12 Nov 2006

Do you have a three port valve on the system? Does HW Cylinder have thermostat. Turn HW on and see if HW stat brings pump on when you turn it up. Check for live at roomstat..assuming you have a mains neon tester BE CAREFUL!!

It may be the three port micro switch not activating on CH setting

Come back to us with more info..especially if there is no three port on the system!

Alfredo

pigeon1974 · 12 Nov 2006

Thank Alfredo,

A fuller description of the system:

Downstairs there is a Glowworm utlimate boiler and Danfoss programmer. At the bottom of the stairs is a Danfoss thermostat.

Upstairs there is a Danfoss junction box with wires going to a thermostat near the bottom of a indirect cylinder, a 3 port valve situated on a pipe half way up the cylinder and a ch pump.

I've checked power to the room thermostat using a neon tester and it appears okay. Upstairs if the thermostat is turned up there is power to the thermostat on the cylinder and to the 3-port valve. But not the pump. I've truned on the hw and turned up both thermostats but the pump does not come on.

Alfredo · 12 Nov 2006

Have you actually checked if the terminal inside the pump is live when the stats are turned up. If live then its a stuck/knackered pump. If not then check/replace the fuse in the fused spur (3 amp) try again. If still no live at pump then the most likely is the 3 port not switching.

To check the 3 port..with both stats turned up (CH & HW on of course) listen to the 3 port as you turn the cylinder stat up and down is the motor whirring/arm moving? Has your 3 port got a manual position for the lever. This should bring pump in

Alfredo

tomy · 12 Nov 2006

the switched live to the boiler and the pump are the same so if the boiler comes on then there should be power to the pump as well unless the pump is wired back to the boiler as some are on low water content boilers as a pump overrun to cool the boiler down

Alfredo · 12 Nov 2006

Quite right about the fused spur being same as boiler..sorry (in my defence we do have some systems on this patch with pump on a seperate switch in the airing cupboard, but its not the way i'd do it)

the rest still applies
Alfredo

pigeon1974 · 13 Nov 2006

Thanks guys.

I've checked the live terminal on the pump and it's not live (after turning the CH on and turning the thermostat up and down).

I'm starting to think it is the valve. It has a manual switch, which has been slack and moves with no resistance. Although now there is resistance.

I haven't heard or seen the valve open or close but I will check tonight and let you know.

Is it fair to assume that if the valve is not working and setting itself to the CH position the pump will not be energised? A quick point when I turn the HW & CH I have hot water and the upstairs rads get hot.

pigeon1974 · 13 Nov 2006

Right, I done what you recommend Alfredo. Turned the CH and HW on. The lever on the valve (as i look at it) is to the left. I Turned the thermostat down not much happened. The lever is slack with no resistance. I turned the thermostat up the valve makes a whirring noise but the lever does not move. If i move the lever to the right and turn the thermostat down the valve makes a whirring noise and moves a quarter back to the left then stops. It doesn't go back right when i turn the thermostat back up - although it whirres.

The valve is not energised at all during this process.

Help! is it time for a new valve and pump?

Cheers!

urbanspaceman · 13 Nov 2006

thermostat on the boiler is your problem my friend

pigeon1974 · 14 Nov 2006

so the thermostat on the HW cylinder conrols power to the CH pump? I've put power on the pump directly and it did not work I think it's kaput.

But I am reluctant to change it 'till i sort out the power.

pigeon1974 · 14 Nov 2006

so the thermostat on the boiler controls power to the CH pump? I've put power on the pump directly and it did not work I think it's kaput.

But I am reluctant to change it 'till i sort out the power. I shall investigate further,

pigeon1974 · 19 Nov 2006

Ok, so if the boiler thermostat is at question but the hw and cw work independent of each other. So my quick fix is to connect the pump to an idependent power supply and switch it on when the ch is on.

Is that acceptable?

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No Power to Central Heating Pump

breezer

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