faulty central heating

[pinkheaduk]

I have a problem with my Central Heating that i hope someone is going to say "thats definitely.......". It is one of those systems with a boiler behind the fireplace and the boiler and gas fire work fine (when they are running).

the central heating wont come on via the timer as normal. When i select the CH overide it just clicks and nothing turns on but the lights come on, If however i overide the HW on the timer then 'sometimes' the hot water comes on. On the occasions that the HW fails to start the pump it sounds like it is stalling i.e. it turns the pump a few turns but can't establish itself. Even when the HW overide does start the pump and i try to switch it to CH it just cuts it out altogether.
I thought it may be the diverter so i changed the actuator but to no avail. As a temporary measure i have taken the actuator off the valve and can switch over from HW to CH by turning the valve but obviously there is a fault (when i can get the bloody thing started).
I noticed yesterday after running a bath that it started by the HW overide first time of asking??

The actuator is a Danfoss HSA3
The timer is a Sunvic 45 i think.

I think it is pressure related or air somewhere........but at present it is proving to be a little bit of a lottery as to if it will/wont start

Any suggestions would be very appreciated

HELP!!!!!!!!!!!

 

[gas4you]

Perhaps then pump is sticking?

 

[bengasman]

back boiler = old = open vent = sludge
no pressure issues on these
as manual trick with valve worked, replace head
clean system once it is going agains as it is guaranteed to pack up sooner or later if not treated
if you are in the 10% that has the system maintained properly, you can ignore the last one.

 

[corgiman]

Just back from two jobs, fingers crossed no more today as I have a rather nice single malt that I really need to caine

just wanted to say WTG Bengas, you aint half dedicated to this here site



merry christmas you nutter

 

[bengasman]

just wanted to say WTG Bengas, you aint half dedicated to this here site

WTG

Have a good one yourself mate, watch out for headaches

 

[technical engineer]

aahh **** it i hate back boiler i cant be bothered with em and they could pottentially get you in trouble even if you check em over with a corgi inspecter

how much did you charge for xmas day call out corgiman id be expecting something at least tempting to get me out my house today lol

 

[corgiman]

Employed mate so I am on double time, gawd knows what the company get

 

[gas4you]

Merry xmas Matt. Even I've not been called out today

 

[pinkheaduk]

Thanks to those who offered suggestions but i am afraid it is back to square one with this!

I have flushed the system through (soaked for two days and then flushed through).....dirty water but not sludge came out.

I have since changed the room thermostat (only because nothing was happening when i was turning it up or down).

The timer is a SUNVIC 50 (not 45 as previously stated).Do these go wrong? is there a common fault? I have changed the two AA batteries in the timer as well.

I have noticed that when i try and turn the Central heating on it makes the pump turns a few turns but also the thermostat clicks???

I have taken the pump off and cleaned it and it works fine.

I can still start the HW and manually turn the three way valve but the HW will only turn on when the tank is cold (after a bath has been run) I have assumed this is the tank thermostat allowing this?

The back boiler was serviced a month ago is there anything that can affect the central heating but not the hot water?

Any more suggestions

 

[JohnD]

when you cleaned it, did you use a sludge-dispersing chemical such as X400?

 

[pinkheaduk]

yes, that is what i was advised to use at B&Q.

 

[JohnD]

OK. Good stuff. 2 days will make a start but on an old system you can leave it in for several weeks. I imagine the water that came out was quite black? you may not have noticed actual sludge as the chemical breaks it up (which is what you want).

old sediment can harden and form partial or complete blockages but the chemical slowly loosens it.

It is also worthwhile baling out the mud from the bottom of the F&E and sponging it clean, to avoid washing that down into the pipes.

 

[pinkheaduk]

So to recap....
I have cleaned the system.
I have replaced the room Thermostat.
I have replaced the Actuator.
The boiler works but trips when i switch it to Hot Water (HW)
I can get hot water and Heating when i remove the actuator and manually switch the three way valve round.
The pump turns when i try and start the heating but stalls straight away.
I have cleaned the pump and it works fine.

The boiler is a Glow worm back boiler and was serviced a month ago.
The programmer is a Sunvic sp50

What else can i try? Could it be the programmer?

Any help would be appreciated?

Happy New Year everyone

 

[pinkheaduk]

sorry my previous entry should read that it trips when i switch to CH and not HW as typed.
sorry

 

[pinkheaduk]

Just to add some other info.
I have been trying to start the CH by using the HW overide button on the Programmer (with actuator removed) for about four hours with no joy.

I have just tried to start it again five minutes after it would normally have been tripped by the programme i.e on at 16-30 off at 9-30 and it started??????????
does this help?