Banging Honeywell V4073a mid position valve when HW demand

[robsinglehurst]

The entire system is about 18 months old. System boiler is Glowworm 24hxi (this controls the pump itself) with a Centaurplus C27 programmer.
Everything works fine apart from getting one loud bang on the pipework on the Port A (radiator circuit connection) when there is demand for HW when the central heating was on last but had switched off before the HW demand i.e. boiler and pump were both off. at the time that there was HW demand.
From browsing a bit here it looks like a Sundial "Y" Plan.
When there is HW demand (or I press the Boost button on the programmer) the boiler and pump start at the same time as the valve changes position and it seems like the water flow is slamming the valve over? Should this happen or should the boiler and then pump start when the valve has finished moving?
I tried switching off the boiler, pressing the Boost button (valve changes position) and then switched the boiler on and there was no banging!
Also if there is HW demand when the CH is on the valve changes position with no nasty bangs.

Any pointers would be most appreciated,

Cheers,

--Rob Singlehurst

 

[hi-spec plumbing heating]

valve finishes its cycle first then fires up.

 

[robsinglehurst]

Thanks,
Is it likely to be a wiring fault or the valve? I think it may have done this from new but I didn't really know any better as I hadn't had a fully pumped system before. Should the Orange wire coming out of the valve go live once the valve has completed it's travel?

Cheers,

 

[corgiman]

I have had this with several HW Mid valves I have fitted recently, the balls (finarr finarr) become loose and whack against the CH port seating

I have changed them all for danfoss valves (paddles dont bang)

 

[hi-spec plumbing heating]

the orange is 230v when heating called for, hw it will only be 100v.

i would say it's a valve problem not wiring

 

[MANDATE]

Hi Spec! I can't see how the orange is only 100volts on HW. How can that be?

 

[ChrisR]

Hi spec - the orange is live from the hw thermostat not the valve, so always full mains and no delay for the valve.
So the pump's pumping when the valve closes, so the valve is driven shut, to a point, by the pump.
I've not known one make a real noise when the pipes are properly clipped. Try that.

 

[hi-spec plumbing heating]

Hi spec - the orange is live from the hw thermostat not the valve, so always full mains and no delay for the valve.
So the pump's pumping when the valve closes, so the valve is driven shut, to a point, by the pump.
I've not known one make a real noise when the pipes are properly clipped. Try that.

ya chris i meant when the hw / heating stats where not calling.

 

[MANDATE]

Just to clarify the situation. There are two wires that supply the boiler. One comes from the cylinder stat and the other comes from the valve (orange wire)
They are connected, so there are two sources to make the orange and connected wires can be 'live'. But they don't both apply at the same time.
For HW or for HW/CH supply is from cylinder stat, but for CH only supply is from valves orange wire.
When the valve fails its usually either motor or micro switch so no supply to boiler from valves orange.
When everything is ok the orange wire is live be it supplied from valve or cylinder stat.

 

[ajs heating]

it's not live when the c/stat is satisfied and the wall stat is satisfied and the grey is 230v

 

[Gasguru]

I have had this with several HW Mid valves I have fitted recently, the balls (finarr finarr) become loose and whack against the CH port seating

I have changed them all for danfoss valves (paddles dont bang)

I've had a new HW mid. pos. banging last week...what's happening with these valves. I find the spindle O ring leaks on the Danfoss after just a few years (even on new clean systems).

 

[corgiman]

I have had this with several HW Mid valves I have fitted recently, the balls (finarr finarr) become loose and whack against the CH port seating

I have changed them all for danfoss valves (paddles dont bang)

I've had a new HW mid. pos. banging last week...what's happening with these valves. I find the spindle O ring leaks on the Danfoss after just a few years (even on new clean systems).

its the old adage mate, damned if you do and damned if you dont

 

[D_Hailsham]

I have edited/changed the order of your comments to make things clearer.

If there is HW demand when the CH is on the valve changes position with no nasty bangs.

With CH only, Port A is held open by the motor. When HW is demanded the valve motors to mid-position and is held there by motor.

I tried switching off the boiler, pressing the Boost button (valve changes position) and then switched the boiler on and there was no banging!

When everything is off (no voltage to the valve or stats) the valve is in its Rest position - port B, HW is open. The boiler is suppled from the cylinder stat, not the valve.

When there is HW demand (or I press the Boost button on the programmer) the boiler and pump start at the same time as the valve changes position

This is to be expected. When there is any demand for HW the boiler and pump are supplied directly from the cylinder stat not the valve.

... one loud bang on the pipework on the Port A (radiator circuit connection) when there is demand for HW when the central heating was on last but had switched off before the HW demand i.e. boiler and pump were both off. at the time that there was HW demand.

If just the CH is on, port A of the valve will be held open by the motor. When CH is satisfied, Port A is still be held open; but there is only 50-100v on the orange wire.

As soon as the HW is called for, the power to the valve is disconnected and the valve shuts port A and opens port B. This is done by the spring in the valve, not the motor.

The fact that you only get one loud bang suggests that it is being generated by the spring returning the valve to the HW only (port B open) position. The ball in the valve (assuming a Honeywell) is being slammed against port A and sending a shockwave down the pipe. One way of checking this would be to temporarily disconnect the feed to the boiler/pump (so they don't run) and then see if you get the same problem.

If it is still there, you could have a valve with an extra strong spring (unlikely). The other possibility is that there is a bend in the pipework soon after the valve on the port A side which is reflecting back the shockwave.

Of course, if the noise disappears, the pump could be causing the problem. Try lowering the pump setting temporarily to see if it has any effect.

PS This will explain How a mid-position valve works

 

[Nige F]

D_Hailsham, I think you are Softus incognito your knowledge, times of posting, and occupancy of a premises in a Neer-do-Well town near God`s Waiting Room (Eastbourne)conspire to fascinate me . I think you must live in the North(posh end) of the town

 

[D_Hailsham]

D_Hailsham, I think you are Softus incognito

I'll treat that with the contempt it deserves.