CH problem driving me mad! Y plan Danfoss pack

[BentheBoatie]

Hello

Installed DanfossRandall Y plan contractor pack.

The HW circuit works fine in all respects, but CH circuit doesn't. Someone put up this table on the forum recently:

ORANGE BROWN/WHITE GREY
OFF 0v 0v 240v

DHWonly 240 0 0

DHW + CH 240 240 reduced

CHonly 240 240 240


I checked these off and they all came up fine, BUT
when I pulled off the actuator head to watch it cycling through the positions it failed to return to the HW only position when I turned off everything at the controller. Cutting power to the controller DID make it return. Is this most likely to be an Actuator or Controller fault?

Also, when I manipulated the spindle of the 3 port valve manually it made the pump sound as though it was having problems when set to the CH only position, and it still failed to get the pipes warm...

Also (!) the Boiler fails to stay alight for longer than a few minutes at a time, especially when set to CH only... under what conditions does the boiler shut down other than over heat? It is a Glow Worm Space saver 52. Would it shut down if it was pushing against flow restriction in the rad circuit ?

Taking all this into account, I reckon I have 3 possible (maybe 4?) problems.

1 flow restriction in the CH circuit
2 Faulty controller
3 Faulty Actuator
(4 sticky valve in 3 port body causing 1?)

Bearing in mind all voltages across actuator seem fine and it cycles through all positions smoothly my opinion is that it is an actuator problem causing it to fail to return to its default HW only position. But it also seems I have a flow restriction causing the pump some problems...

Please release me from this plumbing hell, its getting cold and I live with 3 slightly concerned tenants! At least they can have a hot shower.



Cheers

 

[scatmanjohn]

Hi..Hope someone can answer this one for you cos i am very interested to find out once and for all if mid position valves should return to there rest position by just turning off at the clock. Someone told me they do but i don't think so myself having observed loads that don't unless you totally cut the power at the spur/plug. (or is there loads of installers making the same mistake)

 

[John.B]

When you say you installed a Y- plan pack were you replacing an existing Y-plan that had gone faulty or were you installing one for the first time to the system?

 

[CH4]

... when I pulled off the actuator head to watch it cycling through the positions it failed to return to the HW only position when I turned off everything at the controller ...

It's perfectly normal for the valve to remain in the CH position when everything is switched off at the controller. Whenever the valve is in the mid-position or beyond, an internal microswitch connects its grey wire directly to its motor. The controller's DHW Off terminal applies 240 Volts to this grey wire, and that drives the valve across to the CH position, and holds it there.

It is likely that the CH water not circulating because of an airlock in the pipework. There are a number threads in this forum that discuss refilling, removing airlocks, bleeding pumps, etc., which you may find helpful.

 

[BentheBoatie]

When you say you installed a Y- plan pack were you replacing an existing Y-plan that had gone faulty or were you installing one for the first time to the system?

I moved cylinder from first floor to loft and re fitted associated pipework.

I have an air release on high point of both circuits, and all radiators are showing water at bleed valves

 

[ChrisR]

CH4 you've delved into thse things more than I have.
Have you ever looked into old mid position valves which DON'T stay in the CH only position when the room stat is satisfied?
I'm sure I have come across the odd one but not since I've been looking for one to dismantle.

 

[BentheBoatie]

Ok its beginning to look like a boring old airlock isn't it?

Any killer hints on flushing out problematic airlocks? the system was quite reluctant to drain down...

All 22mm pipe with 15mm tails to the rads, had to put my own drain cock in as there was none present. Its located just lower than ground floor rads on the pipes leading from upstairs circuit to ground floor circuit.

Is it worthwhile trying to fill the system from the ground floor drain cock using a pump up bottle?

 

[meldrew's_mate]

Could it be you have installed the actuator on the valve the wrong way around?

You'll also find the actuator returns to it's relaxed position when the HW next goes on.

 

[BentheBoatie]

Could it be you have installed the actuator on the valve the wrong way around?

You'll also find the actuator returns to it's relaxed position when the HW next goes on.

no, checked that first

thanks all for help, off to drain down and refill...

re: go easy on the gas

I install solar hot water systems, so I help many people do exactly that!

 

[John.B]

Before draining down try this technique. Turn off all rads but leave the one nearest to the pump on. Shut the by-pass while you carry out this job and re-open when successfull. Select ch only and hw off, and see if that rad warms up . If you can then go and turn on the next closest rad and turn off the first rad that you got to work.
By following this action you are concentrating all the pump pressure in to one line of pipework at a time. Again if you get the second rad to work then go and open the third rad and then turn off second rad. Get the idea, you must always have one rad on so that an open path open back to the boiler is available . Good luck, it is a pain of a job though.

 

[ChrisR]

Bounce

(Question for CH4)

 

[BentheBoatie]

Thanks for all your help. I now know how to sort it out, but at a cost!

Every single TRV on the system was jammed shut and so old that when I was messing around with one the rubber valve on the plunger inside disentegrated and started leaking all over the floor... luckily I had a drain on the drain cock in case and I had started on the room with no carpets to be on the safe side!

I believe what had happened was the boiler was just shutting down because all the water was returning too hot, not having passed through any radiators.

It was really a very basic problem. I had already removed the TRV heads and freed the first pin, so I thought I'd done the neccessary, but it was really the plunger that was causing the problem.

Anyway a lesson well learned. Day off work to change TRVs, anyone interested in coming to help? I thought not

Cheersjavascript:emoticon('')