Micron 30FF :: No CH demand but HW demand is fine

[eurodave]

Hi,

I've had a quick look on the forum but nothing seems identical to what I'm experiencing so I thought I'd have a quick ask to see if anyone can help!

I have a Micron 30FF combi boiler that heats the hot water (stored in an insulated tank in the house) and also heats the CH system. The problem is that it no longer sees a demand for the CH even with the thermostat turned up to 30 degrees and the LED on the programmer on to indicate CH demand.

The HW demand is fine and works without issues. The thermostat audibly clicks at around 18 degrees.

Could this be the thermostat or the programmer? Is there any way I can trick the thermostat to output a demand by joining up a couple of the wires?

As an aside: when the HW turns on the radiators also heat up. I presume this is a by-product of the design of the system but it's a bit annoying in the middle of summer - although useful now as it's the only way to heat the house!

Thanks

Dave

 

[seco services]

a micron is not a combi boier.
check your motorised valve sounds like it jammed.

 

[eurodave]

a micron is not a combi boier.
check your motorised valve sounds like it jammed.

My mistake. I should have spotted that.

So the valve would explain why it heats the radiators when it shouldn't, but doesn't explain the lack of demand for CH?

Cheers

 

[seco services]

the valve maybe jammed in mid position so bypassing when only hw on.
if its jammed in mid position it won't make the microswitch when only heating wanted.

on the side of the valve is a lever if you isolate the whole system by the electric fused spur then check if the lever has any resistance on it or is it all loose.

 

[eurodave]

the valve maybe jammed in mid position so bypassing when only hw on.
if its jammed in mid position it won't make the microswitch when only heating wanted.

on the side of the valve is a lever if you isolate the whole system by the electric fused spur then check if the lever has any resistance on it or is it all loose.

ah I see, this is starting to make sense. I will have a look tonight when I get home. So if the electric is turned off then the lever should move freely?

Many thanks for your help

Dave

 

[seco services]

turning power off will put the valve in relaxed position.
then check the lever if it has resistance when you push it its moving.
if the lever is still very loose no resistance that will prove its jammed in mid position and probably seized spindle.

do you know what make of valve it is ?

 

[eurodave]

Hi,

Not sure on the make of valve, but will take a look tonight.

Thanks!

 

[eurodave]

This are the valve details:

"Mid position actuator code"
"BGMVSP-23"
"British Gas NPC code 555312"

However it moves between all 3 positions without issue and at the correct demand when it's connected up.

When the power is off, I can't move the lever (it's small and I don't want to force it).

The pump works when the HW is on demand. It's just not knowing that I want the CH on!

Is there any way I can bypass the thermostat to tell it to turn on regardless of temperature? It's a basic thermostat with a knob and a "click" action and it all looks like bimetallic strips.

Cheers

 

[seco services]

so its moving freely
but if calling for heating only it moves over but boiler/pump won't fire up ?

if this is the case sounds like one of the micro switchs is faulty or the board inside the actuator is faulty. in both cases a new actuator.

 

[eurodave]

yes, it's not loose and moves with resistance at the right times.

with CH only, it moves over to the right position but never sends the signal. with both CH and HW it stays in the middle, so that's what I've left it at as this keeps my house warm

when it moves to the middle there are several "clicks" like a microswitch as you describe. this goes on for about 10 clicks then stops. when it moves to the CH only position there are no clicks. I also don't think there are any clicks for the HW position.

thanks for the help

 

[seco services]

but you also have another problem as you said when only hw on the rads are getting hot, this will be the brass valve letting by so you have now proved the valve is not jammed and is free so can only be crud or the rubber paddle in the valve thats not closing the heating port fully and letting it bypass when only hw called for.
so may be better to fit a complete valve rather than just the actuator.

 

[eurodave]

that's a drayton example of the actuator from what I've seen on the web? looks like I'll be calling someone out to do this job then.

so they are separate issues but will be solved by a new actuator and valve? excellent. Is there any way I can test this before I fork out on all the bits + labour?

many thanks