Hi all new forum member with a bizare heating problem.

[mobilechicane1]

first of all have a round of virtual drinks or however you do it here


So down to buisness, I have a 3 bed semi with a seperate boiler and hot water tank that apears to be heated by hot water passing through a coiled pipe inside the tank.

the radiators apear to be fed from a grundfoss pump that is connected to a 3 way electronic valve ( see below)

now the problem I have is that with the rwb20 controller ( which I have tested and is known good) set to just hot water and not central heating I still get hot radiators.

However with the unit set on central heating only the boiler and grundfoss pump only fire up when there is demand from the thermostat ( i.e the temp is lower than that set on the stat)

There is a blue motorised valve that has 3 22mm pipes running to it one from the boiler the 2nd apears to feed the heater coil input of the tank and the third feeds the grundfoss pump which I assume feeds the radiators.

I have found that the motorised part pf the valve can be uncliped and the little tap it drives turns about 45degrees.

with the tap in the 45deg from horizontal position I seem to get no hot water to the coil in the tank but do get hot to the rad pipe with the tap in the horizontal position I get flow to both outputs.

also the grundfoss pump continues to run and I'm sure this isint pumping hot water round the coils in the tank.

This may have been an ongoing fault as we used to turn the induvidual rad stats down to keep the temp down but then I discoverd that the controller had seperate hot water and central heating outputs.

Any help would be apreciated as this is driving me up the wall

 

[mobilechicane1]

amost forgot the electronic valve has no manafacturer name but it does have the code BGMVSP-23 on it I dont know it that helps.

 

[seco services]

if the programmer is on hw only
feel all three pipes from the valve if they are all hot then the brass part of the valve is passing.
maybe a faulty paddle or crud blocking the port.

the pipe with the pump on will be the pipe from the boiler.
then one pipe to the cylinder hw
and one to the heating.

with a british gas label

 

[mogget]

How old is the heating system / house?

Can you confirm that the pump is fitted to the radiator circuit only? Usually the pump is between the boiler and the 3-port valve, or on the return to the boiler.

 

[mobilechicane1]

thats the valve alright, I'll try and post a couple of pics later on of the set up as I think you may be right about the pump running from the boiler as its downstairs and the hot water tank is upstairs.

need to go to the inlaws now for bh tea

 

[seco services]

need to go to the inlaws now for bh tea

 

[TicklyT]

With the power turned off, does the lever on the 3-port valve head return to it's resting position, or does it stay wherever you move it to?

There should be a couple of springs inside the valve head to hold the valve in the hot water position, marked 'W' on the case, but the fixing pegs tend to pull off the plastic case. You end up with two springs laying loose in the bottom of the valve head, and the valve flapping in the breeze, stopping wherever it feels like when hot water only is selected.
//www.diynot.com/forums/viewtopic.php?p=1152607#1152607

The usual connections to the valve is the output from the boiler feeds via the pump to the valve, and the two outputs connect to the hot cylinder coil and/or the heating circuit, depending on the controller and thermostat states. The pump runs when either hot water or heating is selected.

 

[mobilechicane1]

nice roast pork that was

righto I've taken some hi res pics and whacked them on flikr ( see worksafe linky)

http://www.flickr.com/photos/mobile_chicane/sets/72157618788026672/

checked the valve and the springs are ok, reading all your coments I think the valve may be passing water when it shouldnt ( probably due to sludge build up )

the valve does drive back to what looks like top position when the power is off or when the syswtem shouldnt be giving heat to the radiators.

it also drives to the mid position when rad heat is required.

I let the system cool then fired it up in hw only and found the top 2 pipes ( one fed by the pump the other feeding the top of the tank coil) slightly hotter to the touch than the bottom pipe so I suspect the valve is broken or clogged and therefore wont shut properley therefore giving me hot rads.

The valve is quite easy to acess but I guess to strip and clean it I'll need to shut down the system power to prevent the boiler from runing dry shut off the ball valve to the small header tank in the loft then drain the entire system via the drain valve at the bottom of the rad circuit in the downstairs loo.

am I right in assuming that when I remove the valve itself the compression fittings are a 1 hit item that will weep if removed and refitted, also as the motor drive unit itself sems to be fine can I buy just the valve assy if the unit needs replacing rather than a de-gundge.

the unit looks quite new although there's a small sticker stating that the waranty for the part runs out in 2007


I did have some bad kettling about 6 months ago so I drained the system then flushed it through with some cheap anti kettle stuff from screwfix then put some cheap treatment stuff in it.

 

[seco services]

am I right in assuming that when I remove the valve itself the compression fittings are a 1 hit item that will weep if removed and refitted

they should be ok 9/10 i reuse the same nuts/olives quick clean with abit of wire wool and refit with some jointing compound.

the unit looks quite new although there's a small sticker stating that the waranty for the part runs out in 2007

quite poss its sludge or the ball in the brass valve maybe damaged/faulty.

I did have some bad kettling about 6 months ago so I drained the system then flushed it through with some cheap anti kettle stuff from screwfix then put some cheap treatment stuff in it.

if you goning to use any use fernox or sentinel.

you could put some sentinel x800 or x400 and run for a while then drain and fix the valve same time.

 

[mobilechicane1]

groovy I'll give it a go tomorow if I get home from work at a reasonable time

 

[mobilechicane1]

Hurrah all sorted.

drained the system removed the valve and stripped it down then cleaned all the gundge out of it.

rebuilt refit test and it all works ok.

It was fouled by a small amount of black sludge, whats the best way to de-sludge the system without going down the expensive power flush route ?

 

[seco services]

as said earlier sentinel x800 or x400

least it sorted ans working again.

 

[mobilechicane1]

as said earlier sentinel x800 or x400

least it sorted ans working again.

cheers I'll pick up some sentinel tomorow and whack it in