Baxi Back Boiler - Cannot turn the Radiators Off!

[mrstinchcombe]

I have just moved into a new house which has a Baxi gas back boiler. I can get the boiler lit so I can get hot water but when I do this the boiler also heats the radiators when I dont want them too!

There is a panel next to the water tank that allows you turn the hot water on/off, heating on/off and set a timer but even in the off position for heating the radiators still go on.

There is also a thermostat in the living room but even in the 0C position again the radiators turn on.

Any help would be appreciated.

 

[twgas]

sounds like either a problem with motorised valve or wrongly configured pipework.

do you have 1*3port or 2*2port valves?

does the pipe going from the mv to the rads start heating more less as soon as you turn the hot water on?

 

[maddog1964]

can you tell if the pump is running when on hot water only ie have you got a gravity system as sometime they had a non return valve that could be faulty .

 

[seco services]

gravity check valve not a non return valve.

 

[mrstinchcombe]

I'm unsure what 1*3port or 2*2port valves are but the the pipe going to the radiators start heating as soon as I turn the boiler on.

Again I can only assume due to the position of the radiators that its a pump system not a gravity system. Is there a way to turn the radiator pump off? Where is that normally located?

 

[D_Hailsham]

I'm unsure what 1*3port or 2*2port valves are

3 port on left, 2 port on right. Should be near the hot water cylinder.

View media item 5946 View media item 5945

 

[mrstinchcombe]

I'll check tomorrow which one i've got.

Are the valves easy to replace? I guess I'll have to turn both the electrics and water off and simply remove and replace? Or is there more to it?

 

[D_Hailsham]

I'll check tomorrow which one i've got.

Are the valves easy to replace? I guess I'll have to turn both the electrics and water off and simply remove and replace? Or is there more to it?

When you have told us how many valves you have, we will be able to tell you what to do next.

 

[mrstinchcombe]

It looks like the above 3 port.

What are my options in terms of repariring?

Thanks

 

[D_Hailsham]

It looks like the above 3 port.

What are my options in terms of repairing?

Depends on what is wrong! There are three things which can go wrong: Motor failed; Actuator (box) failed; valve sticking. Here's how you check.

Turn the electricity off to the central heating (Not just turning the time switch to OFF) . This puts the valve back to its default position.

There should be a lever in the side of the valve which can move in a slot; it should be at the Auto end of the slot. Slide the lever across to the other side of the slot. You should feel some resistance. i.e lever not floppy, and hear a whirring noise as you are opening the valve against a spring. When you let go of the lever you should hear the valve closing. If the lever is floppy, the valve is stuck. But this can usually be put right.

Remove the actuator, it will either unclip or have some screws holding it in place. You will see the valve spindle sticking up from the body. Use a pair of pliers to rotate this (it will not go a full circle, just a few degrees either way). If it does not move, try a few drops of WD40 or similar to loosen it. If that does not work you will have to get a complete new valve.

If the valve is not sticking, we next check the motor; leave the actuator off.

1. Set the timer to HW and CH OFF and both thermostats to minimum.
2. Turn the power back on.
3. Turn the HW ON and the cylinder thermostat up. The boiler should light and the pipe from valve to HW cylinder get hot; the other pipe should be cold.
4. Turn the CH ON and the room thermostat up. The motor should run and then stop. The boiler should continue working (it may stop and restart).
5. Turn the HW thermostat down. The motor should run again and stop. The boiler should continue working (it may stop and restart).
6. Turn the HW OFF. The boiler should continue working (it may stop and restart).
7. Turn the CH thermostat down. The boiler should stop.
8. Turn CH OFF
9. Turn electricity OFF

If it fails any of these tests, you best option is to replace the actuator.

But if it passes, we still need to check that the actuator works when on the valve body.

Refit the actuator.

Repeat tests 1 to 9 but also check as follows:
Test 4. Both pipes should get hot.
Test 5. Only the pipe to the radiators should get hot.
Test 6. Only the pipe to the radiators should get hot.

If it fails any tests, replace the actuator. You will get one from any plumbers merchant.

 

[mrstinchcombe]

D_Hailsham, that is a brilliant post, thank you very much

 

[Razor900]

Better add that you should check that the silver cover on the valve has a bump on it, if it doesn't when you undo the screws holding the actuator on you will get very wet.

Otherwise great post Dave