zone valve flow direction

[Lark1]

Hi I wonder if anybody can help with either of these 2 questions?

I think the Honeywell 4043H valves in my central heating are now fitted with the flow in the opposite direction to the arrow on the valve. I say this because we had a boiler fitted a few years ago and I think the flow and return sides got reversed.

The central heating never seems quite right and I've always blamed the 8mm microbore. We had a powerflush a few years ago but we always seem to have unbalanced radiators or cold ones. At the moment all the radiators are fine apart from 2 which are stone cold. The zone valves also leak so I get overhot water if the boiler fires up for the heating.

Up until 30 mins ago I was thinking sludge in the system was blocking the microbore and also stopping the zone valve balls from sealing but now I'm wondering what would be the effect of the zone valves being back to front? Maybe it is sludge-but maybe the the flow is also being restricted by incorrectly fitted valves?

The other question is I bought a spare zone valve on ebay ages ago -thinking I might try and resolve the leaking valve problem. Now I'm giving it a proper look I'm wondering if it is a V 4043H -normally closed or a
V4043B normally open. I say this because looking at the valve with the flow arrow going right to left, the ball is seated on the right hand side. To me that looks like the flow will push the ball off the seating and open the valve?

So basically I suppose what I'm asking is is my plumbing all wrong and have I bought the wrong spare part?

 

[joni os]

Valves normally closed 4043H for gas and oil boilers. 4043B used with solid fuel where failure/ loss of power, leaves valve open as important safety feature.
Reversing valves to accord with flow is straight forward and valves can be checked for function at same time. Also check pump to ensure vanes not clogged.

 

[Lark1]

Thanks joni os . I just wondered how to tell whether the valve that I bought is v4043H or v4043B. There are no markings on it to indicate which it is. Also I wondered if my zone valves are fitted the wrong way round what would happen?

 

[joni os]

If the valve with motor attached and no power is closed it is 4043H. For further confirmation there should be a lever near the underside of the rectangular silver motor housing. If moving this lever against the spring opens the valve 4043H is confirmed.
With valve open flow is possible in both directions but resistance to flow or propensity to malfunction could be greater in one direction than the other. I always assume arrows are there for a purpose.

 

[Unregistered]

Thanks again I think I'll have another look to be absolutely certain but I reckon the flow form the boiler leads to the pump and the pump leads to the 2 zone valves so the flow is from pump to Zone valves. But the arrows on the valves point towards the pump not away from it so against the flow. If I've got this right it sounds like I need to reverse the connnections to the zone valves.

As for the new valve I bought its just the valve body with no power head. I can turn the spindle by hand to open and close it but I just don't know whether it would be normally open or closed. Sorry to go on and on about it but is there a way of identifying the valve body just by holding it in your hand and looking at it?

 

[joni os]

Unless the pump is integral with boiler, changing connections on boiler will only change direction of flow through boiler, not through system. The pump should have an arrow on its casting indicating direction of flow but if this is difficult to locate, confirm direction of flow by starting system from cold, and with valve open determine which side the pipework heats first.
Differentiating between valves in the absence of motorized head is beyond my knowledge.

 

[Lark1]

Ok thanks for your help and advice