Central heating start-up delay

[3port]

Hi all,

I hope you can offer me a little advice?

I have a Y-plan system I believe which uses a Honeywell 5-wire 3-port mid-position valve. The problem I have, happened 3-months ago I think and it has been driving me crazy ever since. It's not a serious problem (yet) but when I switch the programmer to constant with CH and HW on too, nothing seems to happen for several minutes, about 15-30 actually? There is no pump or boiler action in this period.

I do eventually get hot water and heating - it all seems to work fine after that, so it seems like a small problem really - Its just that, why the initial delay?

I'm electrically trained, but by no means a plumber, so I have large gaps in the theory of the design of my system, especially where the 3-port valve is concerned.

The HW seems to work as designed, so I'll put that to one side. So the problem is that when the system is just calling for CH, I get this initial start-up delay. I have checked the room stat and it seems to work ok in so much that when the heating is going, it switches the pump and boiler on and off just fine. Also, the boiler seems to be doing what is asked of it, so back to the valve I guess.

Whilst I was waiting for the heating to kick in today, I started to look at the valve. I have read on this site that the valve has a manual override, so I slide it to the right and it went 2/3 of the way. With some effort, I did manage to get it fully to the right, am I right in assuming that it should be very stiff and offer a lot of resistance, because mine does? I didn't help troubleshoot the problem though. However, I was expecting it to return to the 2/3 position at some point, but all evening I have been able to slide it easily from fully left to fully right - there is no resistance or spring tension as I have seen mentioned before?

The CH and HW "seems" to be working ok, but perhaps its too soon to tell what damage I may have done by forcing the manual override, but in summary: -

1. Can anyone help shed light on the mystery of the CH start up delay - for clarity sake, there is no call for HW at this time, due to the cylinder stat being set quite low deliberately to isolate the problem.
2. How does the manual lever work and what resistance should I feel when the system is in normal operation - i.e. powered?
3. Have I knacked the valve, should I feel some spring tension and should it be replaced?

Many thanks in advance for any advice

 

[seco services]

the valve lever will only have resistance if hw was the last call. hw port open, heating port shut. as the valve will be in a relaxed position.

if you say your lever hasn't had resistance all night is because the heating has probably been the last call so A port open B port close and valve held in last positon by the grey wire hw satisfied or hw off at programmer.

 

[3port]

Thanks for the info my friend, so hopefully the valve is still OK. Can you offer any advice on the start-up delay?

 

[D_Hailsham]

How a Mid position Valve Works might be helpful

I think the valve may have been sticking so it it not opening sufficiently for the second microswitch to change over and put 240v onto the orange wire. You may have freed the valve when you moved the lever to MAN.

On most valves you can remove the actuator (box part) to expose the valve spindle. You can then check that the spindle is free to rotate - but it is only 10°-15°.

 

[3port]

Many thanks again for your advice and the link - The valve does appear to still be working as it was before, so phew - no damage done by forcing the manual lever. I don't think its return spring works though, but not an issue really.

Noting your reference to the 240V on the orange wire, can I just clarify your thinking - do you suspect that if the valve is sticking (impacting the microswitch operation), it would cause this kind of start-up delay symptom for the CH?

Kind regards.

 

[Agile]

Many thanks again for your advice and the link - The valve does appear to still be working as it was before, so phew - no damage done by forcing the manual lever. I don't think its return spring works though, but not an issue really.


Kind regards.

It is an issue as if its not working then the valve will not operate correctly.

It sounds to me as if the spindle is stiff. If it is then it will stop the spring return from working.

You need to take the head off and see if you can turn it with your fingers.

Tony

 

[3port]

Hi Tony, thanks for your advice.

I think I may be confusing things - I was imagining that there should be a spring return on the manual override lever, but I'm starting to realise that perhaps that's not the case. I think the valve's spring return works, as there doesn't seem to be a problem when only HW is called for. Sorry for the confusion.

Hey ho - I guess I just need to time the heating to come on earlier and put up with the start-up delay.

Kind regards.

 

[D_Hailsham]

I don't think its return spring works though, but not an issue really.

If the return spring is not working the valve will never return to the HW only position as it is the spring which moves the valve. If the valve has been in the CH only position (port A open) when the thermostat or timer turns the heating off, the valve will remain in that position. The lever will therefore feel loose. Turning HW only on, or turning off the power completely will reset the valve so it is in the Port B open position. You should then feel the resistance of the spring when you try to move the lever.

Noting your reference to the 240V on the orange wire, can I just clarify your thinking - do you suspect that if the valve is sticking (impacting the microswitch operation), it would cause this kind of start-up delay symptom for the CH?

Yes, I was thinking that there was some friction in the valve spindle which meant that there was only just enough torque in the motor to move the valve very slowly from mid-position to CH only. A bit like driving with your handbrake on. That's why I suggested removing the actuator and checking the valve spindle for freedom.

Just to clarify things, in HW only and mid-position (HW and CH) the boiler receives its power through the HW thermostat. When in CH only the power comes through the valve and the orange wire.

 

[3port]

Thanks for your reply sir - this site is great, you guys are so helpful and the advice is very clear and well written (even if my questions aren't). Many, many thanks for all the replies

 

[Agile]

You need to take the head off and see if you can turn it with your fingers.

Tony

 

[bobe70]

Did this get resolved?

Turns out i have the same issue. I switch my HW on and the boiler fires up instantly. Turn off the HW and switch the CH on and there is around a 15 min delay, it then kicks in and works fine.

When the room stat reaches temperature and clicks the heating off... and then the temperature drop and the room stat clicks on again, the 15 min delay is back.

Is this a common valve actuator issue?

The valve is a Honeywell V4043.

Thanks,

Bob

 

[3port]

Yes - my issue was the 3-port valve. I left the main body hardware in place, but replaced the rest including the electrical components - it works perfectly fine now and no delay.

 

[Agile]

That sounds like a weak motor or chewed up gears.

It is probably more common though for the spindle to be stiff hence my recommendations to remove the head and see if the spindle could be turned easily with fingers!

Tony

 

[bobe70]

Great stuff, thanks for the replies.

I will have a look at the valve spindle and then decide what needs changing... hope this works, those Honeywell valves are £50 a pop!

 

[3port]

Great stuff, thanks for the replies.

I will have a look at the valve spindle and then decide what needs changing... hope this works, those Honeywell valves are £50 a pop!

Have a look on eBay, you'll find brand new genuine Honeywell valves for a lot less than that.