CHeating Problem: Danfoss 3port contractor pack HELP!

[watereed2003]

Hello

Installed DanfossRandall Y plan contractor pack.

The HW circuit works fine in all respects, but CH circuit doesn't. Someone gave me this table:

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

DHWonly 240 0 0

DHW + CH 240 240 reduced voltage

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

[Andrew Gabriel]

I couldn't follow everything you wrote. However, I'll just point out that a mid position valve may well stay in the mid position if you just remove all power from it. To keep the valve in mid-position, the motor is fed with DC to lock the rotor. This magnetises the yoke which can continue to hold the actuator against the spring if you just remove the power (although the holding force is very weak and it will probably release if you touch it). In normal operation, a tiny AC current is leaked through the motor when it isn't operating to degauss the yoke, and ensure the spring returns the actuator to its resting position.

[Set Square]

The valve doesn't always need to return to the HW position when there's no demand - it sometimes stays put. Clearly, it needs to return when there is an unsatisfied HW demand but no CH demand, and it must return when you remove *all* power by switching off at the FCU rather than at the programmer. As long as it does these things, it's ok. [Note that the valve actuator is still powered when HW is off at the programmer - hence the need to switch off at the FCU].

In CH-only mode, the boiler and pump will only run when there is a demand from the room stat. [What is that set at? Check that it's wired up correctly!]. Even then, the boiler will cycle on its own stat if the rads are not dissipating heat as fast as the boiler can produce it.

If the rads are not getting hot, it could be for any of a number of reasons including:

• a blockage in the CH circuit

• TRVs at too low a setting

• manual radiator valves or lockshields turned down too much

• a by-pass circuit wide open - providing a much easier path for the water than going through the rads

• a massive airlock somewhere, preventing proper circulation

There's a few things to have a go at!

[Ed Sirett]

Agreed. I used to name the problem with heating in autumn "The October problem". With the weather this year looking suspiciously like a climate change the problem may have to be renamed the "The November Problem".

The problem is that the weather has got colder not so much in absolute terms but in relative terms. The indoor comfort levels have dropped and we are not yet wearing warmer clothing and/or getting used to being cooler indoors.

However the heating system is not triggered by your comfort level but by the temperature which is still usually enough to keep the heating off. TRVs often keep radiators shut until it's cooler inside.

Also TRVs that weren't set to maximum for the summer months (that'll be

99%+ of them) tend to jam closed.

[gastec]

you have a diverter 3 port valve not a mid position valve....also yo have probably wired it wrong along with a probable air loc

-- gastec

[gastec]

'danfoss%203%20port%20valve%20wiring'oooops you do have a mid position valve..make sure the wiring i correct...see lin

-- gastec