'S' Plan heating problem

[Burnerman]

I'd be so grateful for any thoughts on this one.
Oil fired Rayburn 499K, supplying hot water for DHW and heating; S plan, two 2 port valves, gravity water supply.
The problem is, the hot water to the radiators only occurs until the thermostat on the copper cylinder is satisfied (65 deg)......when this happens, the oil burner shuts down, and won't restart until the tank stat tells it to, or unless I turn the stat up.
The room stat is working fine.
I've replaced the actuator head for the DHW 2 port valve (Honeywell 4043) and this has made no difference. The heating 2 port valve remains open and the circulating pump remains on - and the rads heat fine so long as the burner runs!
The fault has been there for a week or so, no one has done any tampering with things. The only way the householder can keep the rads on is to constantly run off a small amount of hot water
Any tips, anyone please!
Thanks and have a good evening
John

 

[sooey]

You changed the wrong actuator. It's the heating 2 port valve that's faulty.

 

[Burnerman]

Shoot!!
Do tell why....out of me depth here
John

 

[Boilerman2]

Hi John

I'm glad I'm not the only one having a 'mare with a Rayburn PJ Cooker!!
if sooey is correct, then changing the Htg actuator should sort out your problem,
However if not there may be a problem on the rayburn Control panel a manual can be downloaded by Googleing "Rayburn 499K

You have my pity cos I'm in the middle of a saga with a 488K

 

[sooey]

It sounds like the micro switch in the heating one has gone, so when the hot water is satisfied the signal can't get through to the boiler and pump to keep them going until the room stat is satisfied.

 

[Burnerman]

Hi John

I'm glad I'm not the only one having a 'mare with a Rayburn PJ Cooker!!
if sooey is correct, then changing the Htg actuator should sort out your problem,
However if not there may be a problem on the rayburn Control panel a manual can be downloaded by Googleing "Rayburn 499K

You have my pity cos I'm in the middle of a saga with a 488K

Many thanks BM2! I've actually got the manuals - as far as they go - just the wiring centre is a bit of a mess.
I'll stick a new actuator head on the heating side valve.
(The burner in this effort is a NuWay one, (soft start) made for about 2 years so everyone has forgotten about it. It really is a pile!)
Be lucky!
John

 

[Burnerman]

It sounds like the micro switch in the heating one has gone, so when the hot water is satisfied the signal can't get through to the boiler and pump to keep them going until the room stat is satisfied.

Okey dokey, new head on that one it is then!
My flawed logic told me the DHW side was the problem so I'm most grateful for your comments.
John

 

[ianmcd]

Try the head from the DHW one that you replaced if they are both the same make rather than buy a new one

 

[Agile]

I agree with Sooey!

But I also know why you were confused!

You had ( wrongly ) assumed because the pump stays on that the valve micro was making because on a typical heating system the orange wire either feeds the pump directly or it is controlled by the PCB for overun following a call for heat.

Of course I am assuming That either you did not wait long enough for pump over run to cease or its activated from another source!

Amusing I suppose. But confirm this indeed turns out to be the cure!

Tony

 

[Burnerman]

Thanks for that Ian - funnily enough, the actuator I took off was faulty....the gear on the end of the stepper motor were fine, but on the geared quadrant there were a couple of stripped teeth.
This again threw me to thinking I was on the right track
No matter - I'm fitting Toolstation Corgi ones for just under £30 and that will do me.
Cheers!
John

 

[Burnerman]

I agree with Sooey!

But I also know why you were confused!

You had ( wrongly ) assumed because the pump stays on that the valve micro was making because on a typical heating system the orange wire either feeds the pump directly or it is controlled by the PCB for overun following a call for heat.

Of course I am assuming That either you did not wait long enough for pump over run to cease or its activated from another source!

Amusing I suppose. But confirm this indeed turns out to be the cure!

Tony

Yes indeed Tony - and thanks for that!
Truly I am an engineer - but not a heating one Maybe one day!
(The pump over run comes from another source on the boiler circuit board).
I'll post back tomorrow hopefully with good news.
John

 

[Agile]

I have used a couple of those.

They used to sell Tower controls packs but stopped a while ago. The CORGI ones look like Tower too.

I dont see much difference between Honeywell and Tower in quality.

Tony

 

[gaswizzard]

Oil fired Rayburn 499K, supplying hot water for DHW and heating; S plan, two 2 port valves, gravity water supply.

Gravity water supply being open vented?

 

[Burnerman]

Yep - F & E tank in the loft.
John

 

[Burnerman]

A cautiously optimistic update......I fitted the second valve actuator head today, and fired the system up.
After a half hour or so, I went up into the loft, and turned the tank stat down - and the burner kept on running, unlike before! The rads were well toasty.
I'll wait to hear from the punter concerned, but a huge thank you to everyone who pointed me in the right direction.
Cheers and good evening everyone
John