System with 2 zone valves where the one upstairs not fully closing.

[Allecs]

I have a condensing boiler with two zone valves fitted.
One for ground floor and the other one for upstairs.

When heat is called only on first floor, radiators work fine and zone valve does its job. Radiators downstairs are cold( which is how they should be)


When there is no call for heat upstairs but there is call for heat downstairs this is what happends:

Radiator downstairs are hot and working as they should, but the radiators upstairs are luke warm and warm, when they shouldn’t and this is on all the radiators upstairs.

I replaced the motor on the zone valve upstairs and the same issue occured.
I then replaced the whole zone valve and the problem is still present.

Any ideas what could be the problem? Wiring, plumbing, anything

Zone valves are Honeywell if this makes any difference.

Thank you

 

[stem]

One thing you could try, is with the system from cold, switch on the downstairs hating only, when the downstairs radiators start to warm up feel the pipe either side of the upstairs motorised valve. if it's equally hot on both sides then it would appear that the valve is 'letting by'. If one side is hot and the other not, or both sides are cool then that points to it being closed.

Honeywell valves have a spring that pulls them closed, so their usual fault is failure to open. With the heating off, slide the manual lever across to MAN/OPEN, you should feel a resistance as you move it and when you release it you should be able to hear it whirring noise as it moves back to the closed [AUTO] position.

A plumbing problem may be the cause [search 'reverse circulation'] but that would have always been the case unless the system has been modified recently.

 

[ericmark]

I have found with this house, some warmth does come up the feed pipe even when the motorised valve on the return is closed, noticed it during the summer when using the boiler for DHW only, however the cure was to set the TRV's which are in essence also motorised valves, so with the TRV closed on supply and the motorised valve on return both closed, no heat went into the main house, when only the flat being used. Or only DHW being used.

I have questioned the whole point of motorised valves, specially with modulating boilers, the whole idea is analogue control, so the boiler can gradually increase or decrease output, motorised valves are open or closed, so they don't really fit in with a modern boiler, OK with my house, the whole of the flat not used in winter, so except for rare times when we have visitors it remains unheated other than the heat from the boiler its self.

But rest of house we have named rooms office, craft room, kitchen, dinning room, hall, living room, and two bedrooms, and each room has different requirements, having to heat the bedroom when the office is in use makes no sense, so we have 9 programmable TRV heads, and each room is heated independently to the others. Flat still has wax TRV heads, but is hardly used in Winter, so does not matter for the flat.

 

[fixitflav]

Any ideas what could be the problem? Wiring, plumbing, anything

Has it been OK in the past, or have you recently moved in, or what?

 

[Allecs]

One thing you could try, is with the system from cold, switch on the downstairs hating only, when the downstairs radiators start to warm up feel the pipe either side of the upstairs motorised valve. if it's equally hot on both sides then it would appear that the valve is 'letting by'. If one side is hot and the other not, or both sides are cool then that points to it being closed.

Honeywell valves have a spring that pulls them closed, so their usual fault is failure to open. With the heating off, slide the manual lever across to MAN/OPEN, you should feel a resistance as you move it and when you release it you should be able to hear it whirring noise as it moves back to the closed [AUTO] position.

A plumbing problem may be the cause [search 'reverse circulation'] but that would have always been the case unless the system has been modified recently.

The system and pipework has been done 2 years ago.

I can feel the resistence on the valve and this points to working fine.

Difference between the one upstairs(the one with issue) is that if I compare with the downstairs one(working one) is not fully open or fully close when I look at both visually when heating is called, being that independently or together.

Will check what you said and come back with answers.

Thank you

 

[Allecs]

Has it been OK in the past, or have you recently moved in, or what?

Since I moved in has had this problem when the heating is on.

Kind of a let down in regards with the zone valves.

 

[fixitflav]

Since I moved in has had this problem when the heating is on.

So it's possible it's a layout problem, as stem said in #2

 

[stem]

Difference between the one upstairs(the one with issue) is that if I compare with the downstairs one(working one) is not fully open or fully close when I look at both visually when heating is called, being that independently or together.

Not too sure what you mean by that. But, If you are referring to the position of the lever when the valve is opened electrically, the lever just floats free at that point, so it could sit anywhere.

 

[Allecs]

Not too sure what you mean by that. But, If you are referring to the position of the lever when the valve is opened electrically, the lever just floats free at that point, so it could sit anywhere.

I meant that the Ok valve has the lever when open all the way to the right and when closed all the way to the left.

The valve with problems has the lever just a quarter to the right when open and when closed is not all the way to the left.

If I open and close it manually both zones are working correctly