Bizarre - Central Heating requires Hot Water to be active

[Pianoman73]

Just moved into a bungalow, about 15 years old. The heating programmer is a Drayton LP522 which in theory allows HW and CH to be controlled separately. However in practice if the HW circuit is not active and not demanding heat from the boiler, then the CH goes off.

I can affect this by raising the temperature on the water tank stat; if i increase the water tank stat temperature, this calls for more hot water from the boiler, and then the flow to the rads resumes.

Is this behaviour near normal? I'm heating water without any need for it, which is a waste of gas & money. Anything to do with Gravity vs Pumped system? I believe our system is sealed, and I know there is a pump next to the water tank which pumps water to the taps & showers (for lack of any head of water in bungalow)... maybe it also pumps to the rads also, but not sure...

It seems bizarre to me that the water tank stat effectively controls the flow to the rads, and takes the place of the roomstat... does this make any sense to anyone?

I see that the Drayon LP522 has a P for fully pumped setting and a G for Gravity. Is it behaving in G mode?

 

[picasso]

What motorised valves do you have ? should look something like this...


[GALLERY=media, 27205]honeywell 3 port by picasso posted 18 Oct 2010 at 6:15 PM[/GALLERY]

or

[GALLERY=media, 27204]honeywell 2 port by picasso posted 18 Oct 2010 at 6:15 PM[/GALLERY]

 

[Pianoman73]

thanks Picasso, i checked and it appears there are no such valves visible in our airing cupboard, where all the other pipework is visible. There are gates (red wheels on top), but no valves... I do have a Duraspeed shower pump in there

 

[picasso]

I cant see your hot water being gravity if your bungalow is only 15 years old, plus the fact the cylinder needs to be above the boiler to work on gravity, have another look for valves.

 

[Pianoman73]

thanks Picasso for pointing out it's the motorised valve at fault - we'll look for that until we find it! I note that screwfix also has quite a few images for us to look for. http://www.screwfix.com/c/heating-plumbing/motorised-valves/cat831028
An engineer once advised me to hit it firmly, which can free it from its stuck position... is that advisable?

 

[picasso]

It won't be stuck, more likely its a microswitch fault .

 

[Pianoman73]

thanks once again for your kind advice, Picasso. If we locate it, i'll come back to you...

 

[Pianoman73]

I managed to find the "iflo MA1 Mid Position Actuator" motorised valve in the loft, wiggled the levers sticking out of the side of it, and hey presto hot water is now passing to both the hot water tank and the central heating. Turned the stat down on the hot water tank to make sure that the CH works independently of HW.

 

[DaveHerns]

If that's a Drayton MA1 valve , change the actuator. 5 wires to connect and the head just clips on to the valve

 

[Pianoman73]

It's an MA1 for sure, it's looks very similar to the shape and size of the Drayton MA1. I'm guessing that Drayton merged with iFlo at some point. Because of where it's installed in the loft floor this is the best shot I could get..

 

[leakydave]

iFlo was a trade name used by City Plumbing/Travis Perkins and is a Drayton Valve I believe.

 

[Pianoman73]

@leakydave, replaced the MA1 679 actuator on 22mm pipe and now all is well. Many thanks indeed.