CH/HW 2-port valve failed?

[nigel.l.jones]

I appear to have an S-plan CH/HW gas system, with 2 x 2port valves.

In the last few days the hot water has stopped heating (although immersion is fine, as is heating)

I first tried bypassing the hot water cylinder thermostat - this made no difference.

I believe therefore that the 2port valve leading to the HW cylinder has failed.

The valve is a ACL Lifestyle, 28mm. There is an A/B indicator, which stays on A. There is also a manual level I can push, which causes the indicator to move 1/2 way to B. If I do this there is a click of a microswitch and the pump / boiler activates fine. If I let go the lever move backs to A and afte ra while the pump/boiler will stop.

My son reckoned he saw it move 1/2 way to B and immediately back again when HW was turned on, but I've not been able to see this myself. It's always on A.

I am guessing therefore that the actuator motor is not operating. I've not checked the wiring yet, but it's probably failed?

On starting to removing the cover, I was hoping the whole actuator might unclip - but instead it seems as if only the plastic cover comes off, with all the "business" left attached. I've not yet examined if in fact this can be removed dry.

Does anyway know if on the ACL Lifestyle it can be removed/replaced easily?

I'm not a plumbing fan, so given that I also am in need of a boiler service, am considering getting BG etc to start a contract. A few years ago I believe they charged extra if an existing fault was present. Now all I can see in the T&Cs for cover is

--start-- Design or existing faults

The cost of repairs needed because of design faults (unless we are responsible), or faults which existed before you entered into the agreement and which could not be identified on initial inspection using reasonable care and skill.

--end--

Does this mean they'll charge for faults found on initial inspection? Or that they won't worry about it?

I would expect I'm looking at around - =A360 boiler service - =A340 new valve/actuator - =A380 labour

?? in any case, making the BG approach reasonable.

Comments?

[Set Square]

I don't know this particular valve, but most motorised valves have actuators which can be replaced without disturbing the wet part of the valve. Check the wiring to make sure that the valve is actually being told to open. If it is, the most likely explanation is that the actuator motor has failed. Screwfix do a synchron motor for under 8 quid which fits certain ACL Drayton actuators - check whether it fits yours.

The general concensus in this NG is that you shouldn't touch BG with a bargepole!

[colinrming]

I too am having problems - but am not certain whether it is the valve (ACL LIfestyle 779H 340 3OLO 3 port mid position valve), the control panel or the PCB board in the boiler. I have contacted both manufacturers of the control panel and the valve and of course, each says that the others equipment is at fault! The problem is occasional and includes:

1. Manual CH override did not work. So, tried HW override which did work. Turned this off after a few minutes and then tried CH override again. This time is worked.
2. On another occasion, CH override was utilised. The HW then came on automically (clcok setting). However, when teh HW went off (clock setting) it also took the CH off with it - even though the CH override light on the controller remained on.
3. CH did not come on at the programmed time - although the thermostat clicked on in the hall. Also, the CH light lit up on the control panel. CH would only come on if HW and CH overrides were put on together. As I said, Drayton think the control panel must be at fault whereas Danfoss (control panel)advise that the motorised valve is the most likely cause of teh problem. So, an independent view would be much appreciated before I fork out a lot of cash.

By the way, the valve mentioend above must be replaced in its entirity. I am advised that the replacement is the MA1-779-3 (28mm). Thanks

Colin

[colinrming]

I too am having problems - but am not certain whether it is the valve (ACL LIfestyle 779H 340 3OLO 3 port mid position valve), the control panel or the PCB board in the boiler. I have contacted both manufacturers of the control panel and the valve and of course, each says that the others equipment is at fault! The problem is occasional and includes:

1. Manual CH override did not work. So, tried HW override which did work. Turned this off after a few minutes and then tried CH override again. This time is worked.
2. On another occasion, CH override was utilised. The HW then came on automically (clcok setting). However, when teh HW went off (clock setting) it also took the CH off with it - even though the CH override light on the controller remained on.
3. CH did not come on at the programmed time - although the thermostat clicked on in the hall. Also, the CH light lit up on the control panel. CH would only come on if HW and CH overrides were put on together. As I said, Drayton think the control panel must be at fault whereas Danfoss (control panel)advise that the motorised valve is the most likely cause of teh problem. So, an independent view would be much appreciated before I fork out a lot of cash.

By the way, the valve mentioend above must be replaced in its entirity. I am advised that the replacement is the MA1-779-3 (28mm). Thanks

Colin

[Wingedcat]

Colin

Go back to basics.

Set room thermostat to hottest, tank thermostat to hottest, open up all TRVs to the max and make sure programmer says HW off and CH off.

Get yourself a multimeter and identify the Call for Heat input on the boiler. This should be simple, the incoming connections will be Live, Neutral, Earth and Call for Heat.

Activate the HW using the Override facility on the programmer. Call for Heat input on boiler should now become live. Boiler should fire, pump should start, Mid-position valve should be in HW only position which is "at rest", i.e. there should be a significant resistance when trying to move the lever on the valve by hand.

If you get no Call for Heat signal, either the programmer or the wiring in between is knackered. If the boiler doesn't fire or the pump doesn't circulate, you have a boiler / PCB problem. If you get CH instead of HW, or if you get CH and HW, then your mid position valve is knackered. (feel the pipes coming from the mid position valve to confirm which position the valve's in).

Turn off HW and activate CH.

As above, you should get a Call for Heat signal, boiler should fire, pump should start. This time the Mid-position valve should be fully activated, i.e. there should be no resistance at all when trying to move the lever on the valve by hand.

Other results can be interpreted as above. If the valve is not fully activated then it is knackered. You will most likely get HW instead or a combination of CH and HW.

Turn on both CH and HW.

Results will be as far CH only but the mid-position valve will now be in a central position and both pipes from the valve will become warm.

If all these results check out okay, then your boiler and associated plumbing and valves etc is working fine, and the problem is with the programmer. Easy!

Luke