3 port valve

[Geeday]

In short: when ever i turn on just HW on my CH system, the rads get warm. I have just replaced the actuator head (a 4 wire one) of the valve and I believe this is working correctly: i.e. the motor spins when I turn the CH on, then returns when i turn it off. We have manually turned the valve (without the actuator head) in to a position that doesn't allow the rads to get warm, but we can get hot water. We have married up the ports (A/B) on the actuator and valve itself and have to assume it was installed correctly (we have just moved in). Could the valve be bunged up (it spins OK using fingers) or could the mounting plate be 90 degs out? I believe the previous owners who lived there for 3 years just turned on the immersion when they wanted hot water so i dont know when it was last used properly. Hopefully someone can decipher my message.

Thanks

Gordon

 

[AlanE]

Could be that the valve is letting by which means the actual valve body will need replacing.

 

[croydoncorgi]

When you say rads get 'warm' do you mean all of them? some? one? and warm or hot? Do you think the valve is actually 'deliberately' turning on to heating, or just leaking a bit? Also, is this a Honeywell 4073 valve, or something else?

 

[Geeday]

There doesn't seem to be a leak, more like full flow through the valve, all rads heat up. Not sure what sort of valve it is. The original actuator that was broken (didn;t rotate when requested) was by Satchwell (SD1751), we are talking 20 years old i reckon and the water isn't "very good".

As mentioned we have found a position where we can isolate the HW from CH but it is impossible to fit the actuator on as the fixing holes on the mounting plate do not agree with it. We have moved the valve every 90 degs and looked what happens, but we are not sure of the inner gubbings of the valve.

 

[gas4you]

Think you'll find you need to replace the complete valve and head., although a niggling feeling tells me that a sunvic may fit on the body. Not too sure.

 

[croydoncorgi]

At that age and where the exact type of valve is uncertain, you'd probably be best advised to change the whole thing. If you did actually find a replacement head, the valve body would probably take revenge by leaking the next month!

Make sure before you start that the valve type you need is a 'mid-position' type (rather than, for example. 'motor-open, motor-closed). If it IS a different type, you'll need to do some rewiring too - but I'd still fit a Honeywell 4073.

 

[giblets]

Might be worth checking to see which end of the rads get hot when you only have the hot water selected. If it's the opposite end to that which gets hot when the CH is selected then you may be suffering from reverse circulation normally caused by the return connection from the hot water cylinder not being the last one connected into the return pipe before the boiler.