Mid position valve British Gas BGMVSP-23

[maxfox44]

Hi Guys

I have tried to search for my answer, having read a few similar threads, I just need a little but more advice.

Last year the actuator failed and I have been on the manual lever for heating since then. The lever takes a bit of pressure to pull it across and makes that forcing a motor sound. But works okay.

I'm now getting a bit of aggro from her indoors to sort this.

This link, suggests that this unit is a direct replacement for the British Gas BGMVSP-23 and I have had the head off and it does just snap on.
http://www.heatingcontrolsonline.co.uk/acl-drayton-invensys-ma1-actuator-p-112.html

Should I be able to turn the valve with my fingers? Should I drain down and replace the whole valve and actuator?

Thanks in advance.

Max

 

[Agile]

I thought the FAQ would have had all the answers.

Thats expensive but will suit.

You should be able to move the shaft with your fingers.

Tony

 

[maxfox44]

Tony

I really appreciate your reply.

I can move the spindle, but not more than say 1/8 turn. Didn't want to get the grips on it.

When you say expensive, where can I find a cheaper alternative.

 

[MANDATE]

If you have to use the lever, it suggests to me it's either (a) the motor is the problem or (b)motor not receiving any power from the room stat.
Are you saying the valve moves from mid position to CH position, which would mean motor ok

 

[maxfox44]

I'm pretty sure it's either the motor or the micro switch or both. My real question is whether to just get another actuator (like the one in the link) or have the whole thing changed.

Did it burn out because the valve had siezed? Or natural life-span.

Everything works on the heating and hot water system, a part from switching to heating when it's previously been on HW.

If I manually move the lever then turn on the heating and move the thermostat it works perfectly.

 

[MANDATE]

The motor won't have burned out due to seized valve. The way it operates is always against an opposing force.
It works over two sections
(a) power from room stat supplies 230v to white wire of valve to drive motor to mid position where it is 'stalled' either momentarily or until required to go to CH
(b) power from cylinder stat or programmer HW OFF supplies 230v to grey wire of valve which then drives motor forward to CH position. prevented from going further by 'stop'. So motor remains energised and that remains so even when room stat has closed boiler down.
If no power was present on the grey when in mid position the motor is still energised with a modified voltage sufficient to hold it against the return spring

 

[maxfox44]

I was thinking of buying the whole unit from say Screwfix and then just replacing the head in the first instance. Do you think that is a good start?

 

[MANDATE]

Because there are 2 micro switches with 4 pair of contacts, any of which can cause problems, plus a motor, I do agree replacing the actuator head covers almost everything. That is providing the wiring and the room stat are correct.

Just be aware when HW and CH are turned off, there is still a live wire going to the grey in the actuator head, so make sure all power is removed while making the change

 

[maxfox44]

Thanks.

So by isolating the power to the boiler/heating system, I should be okay. Pulling this switch moves the lever, suggesting that power is cut, right?

 

[MANDATE]

Yes isolate power to boiler, but you should always test to make sure.

It won't have any affect on the lever. The lever is there for a different purpose. When system is re filled after draining water is required to enter both HW and CH circuit and it cant do that unless valve is in mid position, so lever is provided to move dead motor to mid point where it is latched during filling and afterwards returned to 'auto'. So the lever is loose and gets left behind when the motor operates as far as I'm aware

 

[maxfox44]

Finally and you have been a great help.

Is this the right actuator to replace the blue British Gas BGMVSP-23?

http://www.heatingcontrolsonline.co.uk/acl-drayton-invensys-ma1-actuator-p-112.html

I was going to snip off the existing cable and join in suitable rated junction box.

Can you think any anything else I should be aware of? Or a cheaper place to purchase said item?

Thanks again.

 

[MANDATE]

It appears to be the correct replacement.
The junction box idea is ok, I've used it for 'actuator head' and 'circulating pump'. makes it easy for testing or powering up from a separate supply.