boiler problem. hot water but no central heating?

[craig20102010]

So I have a baxi boiler which has been working fine for a while now. All of a sudden its stopped providing central heating.

Hot water works fine still but as soon as central heating comes on it heats the water up fine but then over heats more then the set temperature iv set it too like 75c then clicks constantly on and off. Pressure doesn't drop on the gauge when central heating kicks in like it used too.

The only way I can stop it clicking and switching is to turn heating off and turn the hot water tap on to bring the temp back down. If it then goes too low the gas comes on and the hot water works as normal. But central heating continues not to work when I turn it back on.

Faulty pump?

Thanks Craig.

 

[Crezzer]

Is it a duotec? Does the flow pipe get hot when you call for heat? Sounds like the diverter head isnt doing its thing.

 

[craig20102010]

Yeh its a duo tec. Its a about 10years old now. Not sure if I can tell which one the flow pipe is. All I know is it starts heating the water up and you can hear eveything kick in like the pumps on etc but the pressure doesn't drop off and you can hear something constantly clicking on then off while the temperature is sitting around 75 when iv set it to a maximum of 60.

 

[Crezzer]

Theres 5 copper pipes under the boiler, the one on the far left is the flow pipe this should get hot quite quick when the heating is on, if it doesnt it sounds like a diverter problem.

 

[craig20102010]

No it doesn't get hot its just Luke warm which is certainly wrong as its displaying 70c on the front so I'm assuming that's just heat transfer through the valve that heat. The pipe i held had a radiator symbol on it with arrow pointing down. The other pipe at the oppersite end with a radiator symbol on it with arrow pointing up is quite warm too.

 

[Crezzer]

Its a diverter valve problem, you'll need a professional in to fix it.

 

[craig20102010]

Can I replace just the solenoid part of the valve. Iv found the cartridge for my boiler online and its a lot cheaper then replacing the whole valve and its obviously that which is sticking in the hot tap position.

 

[Crezzer]

Is yours the one with the black square motor?

 

[craig20102010]

Can't seem to see the pump is it on the right hand side? Can't see anything square in there looking from underneith .

If I'm looking at the correct thing its round and black on the right hand side.

The model of my boiler is the duo-tec combi 28HE A. And when I had a look online my model was listed unless it has a bypass.

Looking on the left hand side above the diverter valve there's a little square cream bottomed box. Black on top. Cable coming out toward the front of the boiler.

 

[Crezzer]

Take the white boiler front off, inside on the left hand side you'll see the motor, sort of a black square thing held in place by a little clip, pull the clip out and the motor comes off, the motor pushes on a pin to move the diverter. Turn your heating on and you should see it push out if it doesnt or the motor rattles then I would say its broken. You wont get wet doing any off the above.

 

[craig20102010]

Thanks I'll have a look at this. Seems simple enough. I'm guessing this is the Motor for the diverter and not the motor to pump the central heating round.

 

[Crezzer]

Yes its the diverter motor, if your pump was faulty you'd have no hot water and the boiler would flash a fault code.

 

[craig20102010]

Ah right I thought the pump only worked for the central heating and the tap hot water worked off mains pressure.

You've been very helpful I'll report back when I have time to have a look into removing it.

 

[craig20102010]

So iv had a look at the motor. I can't seem to remove the clip that holds it on. Its jammed in solid and I don't want to pul it too hard to get it out. Looks like it's been leaking as well. Alot of corrosion around the clip.

diverter valve on baxi 28he a

• craig20102010
• 29 Sep 2014
• 1

So since then iv managed to get the clip out although its left some of the clip inside it. Meaning I can't get the actuator off as the clip is still holding it in on one side. Very annoying. Wish it hadn't corroded over. At least I have a rough idea what the problem is now. Either the valve is screwed or the actuator. Judging by the rust itll be the valve internal leaking past the seals.

 

[Crezzer]

Ah yes, its been leaking and if you just swap the actuator it might not last that long. The guts of the valve do unscrew and you could then screw new ones in if not you'll have to change the whole body. You will need to drain the boiler to unscrew the guts and if you change the hole lot you'll have to isolate the cold. The screw on the bottom will probably be all corroded which will make changing the body tricky.