I'm getting Hot water but not Heat

[lilelvis2000]

I have a old style Hot water and CH system. I have the cylinder in the airing cupboard with the pump and divertor valve. The system is about 15 years old but never gave any trouble so far.

I've recently noticed that the CH no longer comes on even if I turn the thermostat to max (30). I had this problem last year but I replaced the thermostat and that cured it. So this time I did the same but the problem persists.

Hot water is working just fine. the pump comes on and the diverter valve is in W position & boiler switches on. With only CH on the pump does not come on and the diverter is still in W position. Makes no difference if both CH and HW are on at same time. I only get the boiler coming on to make hot water but not when I want heat.

I'm not sure if the problem is the controller (Drayton LP241) or the box in the airing cupboard which the pump and diverter are connected to. The controller is only £35 so I might just take a punt and replace.

How would I go about diagnosing the fault to determine which bit has failed. I don't have a multi-meter but I do have a probe that can test for power.

Thanks for any help.

 

[muggles]

You'll need a multimeter and a certain amount of electrical knowledge to test this, if you don't have either then it'll be better to call someone in than keep throwing parts at it in the hope that you can fix it

 

[lilelvis2000]

realize that.

I have found a wiring schematic for a Y system. So I know to check the white wire from the thermo. to the zone valve, check the grey wire. and check the brown wires to the pump and boiler.

BTW manually moving the valve does not kick the boiler and pump on. switches and motor gone?

if it is just the actuator, can that be done without draining down the system?

 

[muggles]

If it is just the actuator then it depends on the make, some can be changed without draining the system but others aren't removable and need the whole valve to be changed

 

[stardanny]

Have you checked there is power from thermostat when switch on?

Does not have to replace actuator, just replace the motor inside.

See what happen when you switch heating on only and manually moving to heating on valve?

Daniel.

 

[lilelvis2000]

It is a Drayton 3-port valve and the website says the motor and switch can be replaced separately.

Going the check the white wire...but as its late...and its summer I'm in no rush. Plus my testing equipment is in my office and this problem is at home.

It does seem suspicious that when I put valve in mid-position, and the thermo. is on max (and it clicks at about 20C) that the pump and boiler don't come on. Like there is no power from the thermo.


I'll post results over the weekend.

 

[lilelvis2000]

Results:
CH on.
Thermo on Max.

White wire to valve 240v, Gray wire 240v. Orange wire 0v. I think that confirms that it is the actuator. When I put the valve in mid-positon. the results are the same.

HW comes on. grey wire 0v and the blue wire to boiler and brown wire to pump 240v

So is the whole actuator gone?

Its a drayton ACL Lifestyle 22mm MId-Position valve. 679H340-30L0 which I believe the head just comes off after prying the clips gently and loosing a screw on opposite side? and is replaced with a Drayton MA1/679 actuator?

Odd that the motor and micro-switch have gone at same time. Any chance there is a internal fuse that's gone and just needs a replace?


Any tips?

 

[jeff the gasman]

Just replace the actuator or if are handy replace the synchron motor instead. They are around the £12 mark.
Jeff

 

[lilelvis2000]

Unfortunately the MA1 actuator is not compatible with the valve body - the newer actuators have a plastic clip on the bottom which fits into a groove on the body.

I'd need a compatible actuator to the one I have, or find a new one somewhere (good luck).

I could swap the innards I suppose. That I could do as a last resort. Well call a plumber out to drain system and replace valve.