Help central heating not working!!

[Hobbernobber]

Hi, I have a gas central heating system with a Baxi boiler.. the hot water works fine but the central heating is not coming on at all, I have been having problems with it for quite some time now, but have been able to get the central heating to come on by letting a hot tap run for a while to get the boiler to fire up and then the central heating would also come on. But this solution is no longer working and although the boiler fires up when I run the hot water for a while the radiators do not heat up? Any ideas would be much appreciated as my wife is complaining about the cold!!!!

 

[jackthom]

Hi what is the model number of the Baxi and do you have a room thermostat fitted ?

 

[buck51]

Have you checked the pump / thermostat???

 

[Hobbernobber]

It is a Baxi Splo 3 pfl 50, there is an old satchwell thermostat fitted in the hall. The pump sounds like it is working, and the thermostat clicks when I turn it.. so I assume it is calling for heat?

 

[jackthom]

Next question are there any motorised valves similar to these in the system.

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• jackthom
• 19 Dec 2008
• 18

OR

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• jackthom
• 4 Nov 2011
• 5

 

[MANDATE]

Although not stated it sounds as though you may have a 3port motorised valve, which goes to mid position but does not go to the CH position. If it does go to CH position, then faulty micro switch most likely at fault.

When you run hot water off, a demand for HW is created as well as that for CH. The valve will either stay in mid position (if it never moved on) or drop back to mid position and then you will get both HW and CH.
This of course will only las t till HW is satisfied again when valve should move to CH.
Replacing the actuator head usually solves the problem

 

[Hobbernobber]

Next question are there any motorised valves similar to these in the system

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• jackthom
• 4 Nov 2011
• 5

Yes there are two motorised valves like this one ^

 

[jackthom]

OK, one valve opens up when the boiler is heating the hot water tank and the other is for the central heating.
See if you can identify the one that leads to the radiators and see if it opens when there is a demand for heating.

When it's open the lever on the side will be easy to move and when it's closed the lever will be harder to move across and will slowly spring back to the closed position.

When heating is required power gets fed to the valve motor, it opens and when it's fully open it triggers an internal switch which should run the pump and boiler.

If it isn't opening automatically you can move the lever to open it manually and lock it in the open position to see if that gets the boiler firing.

 

[Hobbernobber]

Thanks, I think I have figured out which valve is for the central heating and it seems to be stuck, I have tried sliding the lever to manual but it won't move beyond the halfway point at all! Does this mean I need a new valve?

 

[jackthom]

Provided the valve isn't more than 20 years old it should be possible to remove the actuator head (with all power turned OFF) without losing any water. Then you can check out the actuator mechanism and attempt to free up the valve spindle if that has seized.

The spindle won't move more than about 70 degrees so avoid forcing it too much. When free it should normally turn easily by hand.

A bit more reading on that here....

http://www.lovekin.net/honeywell-motorised-valve-faults.html

 

[Hobbernobber]

Provided the valve isn't more than 20 years old it should be possible to remove the actuator head (with all power turned OFF) without losing any water. Then you can check out the actuator mechanism and attempt to free up the valve spindle if that has seized.

The spindle won't move more than about 70 degrees so avoid forcing it too much. When free it should normally turn easily by hand.

A bit more reading on that here....

http://www.lovekin.net/honeywell-motorised-valve-faults.html[/QUOTE]

Thanks again, I have been messing about with the valve and spindle for quite a while trying to get it to move without any luck. But all of a sudden the heating has come on and when I checked the valve, the lever now moves easily with no resistance at all!! So I will leave it for now and see if it comes on again tomorrow, but I doubt it as this is the first time we have had heat going to the rads for nearly 2 weeks. I'll let you know what the situation is tomorrow sometime, if it wont open again, I will remove the actuator head like you advised. Thankyou

 

[Hobbernobber]

Eventually I turned down the thermostat as it was getting too hot!! When the valve had closed I tried to slide the lever along to manual, but I was still unable to shift it... But amazingly the central heating came on all by itself this morning, so I will leave it for now and see how it goes, but as soon as it starts playing up again I'm going to change that valve!

Thankyou for all your help guys, especially Jackthom.. it's very much appreciated!!

 

[Hobbernobber]

Once again thanks for the help last month, unfortunately I am again having problems with the central heating!! About a week ago I turned the water on to try and get the boiler going, the boiler came on but the slider on the motorised valve would not slide across, so I gave it a bit of a thump which did the trick and it slid accross and the radiators heated up!! But now the valve just stays open all the time and the radiators only heat up whilst the water is heating, once the water is hot enough the boiler just switches off and the radiators go cold!!!

Any ideas as to what I could do as we are freezing, and seem to be constantly running the hot water to get the central heating to come on for a few minutes!!! Help please!!

 

[Hobbernobber]

Any suggestions please?

 

[Hobbernobber]

Perhaps I should start this as a new topic? I got a helpful reply almost immediatley last time, feeling a bit dissapointed this time!