Banging from Motorised Valve

[andymck]

Hi, my home hot water and central heating system is implemented with a Danfoss Randall Fp715 si HPP system...see link below

http://www.plumbitcentre.com/epages/BT3194.sf/en_GB/?ObjectPath=/Shops/BT3194/Products/000006


The heating system is an oil based sealed System with a conventional boiler. The pressue is set to 1 bar, 0.5 bar at rest. The pressure pump is set to 2.

Ever since it was fitted ( by the builder ) we have been getting sporadic banging noises from what appears to be the motorised valve. It mostly seems to occur when the CH comes on or when it goes off again and can continue for hours on end, getting progressively worse. The noise can be heard throughout the house.

The only way to stop the banging noise is to manually switch on the HW and leave on for about 10 seconds and await for motorised valve to move position ( sorry i am not a plumber, heating engineer etc and dont know the correct terminology here ).

We have had the motorised valve replaced twice and still no change and have had numerous plumbers out to look at it. They all say its the valve, replace it and same story. I have noticed that none of the guys we have had out really seems to have clear knowledge of how all these things are supposed to work. Could it be the port the motorised valve connects to ? Could the thermostat be incorrectly wired ?


Any help or input would be much appreciated. I can upload pictures of the wiring of the WB12 box and video of the banging and how we stop it continuing.

Thanks

Andy

 

[D_Hailsham]

Presumably just the one 3-port valve - like this:

View media item 5946

What is the make and model no of the valve?
Is it connected the correct way round - Port A to heating, port B to HW cylinder (port letters are on the brass body)?

 

[andymck]

Hi, thanks for your reply.

Port A is connected to the CH and Port B to the HW.

I cant spot a make on the valve but its model number is HSV3, see photo below:

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• andymck
• 30 Nov 2009
• 1

Any further advice very much appreciated.

Andy

 

[seco services]

its a danfoss its on the side.

 

[D_Hailsham]

Valve is connected correct way round.

Which make & model boiler do you have?
What speed it the pump set to?
Do you have thermostatic valves on the radiators?
Do you have an automatic bypass?

 

[andymck]

Heres an image showing the plate on the boiler and its make and model info

Untitled

• andymck
• 30 Nov 2009
• 1

The pump is set to "2". Have also tried it on one. Havent tried three yet as two was very noisy.

There are no thermostatic valves on the radiators

Not sure if there is an automatic bypass on the boiler, how can i check this ?

Thanks

Andy

 

[andymck]

Just had it confirmed there is no auto bypass....

 

[andymck]

Tried setting pump to all settings 1,2 and 3 and the banging occurs on all 3.

The fact that the banging stops when the HW is switched on and after the motorised valve moves position surely indicates that something is faulty either with the motorised valve head (part HSA3) or the valve (plumbing part "HSV3" ) itself ?

In my first post i mentioned that we have had the motorised valve replaced twice already, i want to clarrify that by saying that we had the motorised head part replaced but never the "plumbing part"...

 

[picasso]

can you post pictures of the valve, pump and any thing else connected so we can see how the system is plumbed in.

 

[andymck]

here ya go:

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• andymck
• 1 Dec 2009
• 1

Untitled

• andymck
• 1 Dec 2009
• 1

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• andymck
• 1 Dec 2009
• 1

Untitled

• andymck
• 1 Dec 2009
• 1

Excuse the dog hairs that have gathered round everything! Really must pull ev thing out and clear it all down.

 

[D_Hailsham]

In my first post i mentioned that we have had the motorised valve replaced twice already, i want to clarify that by saying that we had the motorised head part replaced but never the "plumbing part"...

How old is the valve body, i.e. the "plumbing part"? Is it as old as the rest of the system appears to be? If so, the noise may be due to the innards rattling around because it is worn out.

 

[andymck]

Its about 10 years old now i guess.

If it is the innards being worn out, why does it stop banging when i click on the HW? Should i not notice some issues if the innards were dodgy, i.e. the HW not going to the tank or the radiators?


Thanks

Andy

 

[D_Hailsham]

If it is the innards being worn out, why does it stop banging when i click on the HW?

It's the way the valve works. When CH has finished, e.g turned off by the room thermostat, the motor continues to hold Port A open. So if anything is loose inside this might rattle. When you turn HW on, the motor is disconnected and the internal spring takes the valve back to its "rest" position - Port B open. The spring is strong enough to hold the valve closed without ratting.

If you decide to change the valve, get a Honeywell V4073.

 

[andymck]

ok, i will replace the valve. Thanks for your advice.

 

[blushy]

It's the way the valve works. When CH has finished, e.g turned off by the room thermostat, the motor continues to hold Port A open. So if anything is loose inside this might rattle. When you turn HW on, the motor is disconnected and the internal spring takes the valve back to its "rest" position - Port B open. The spring is strong enough to hold the valve closed without ratting.

Sorry to butt in but you hopefully can answer my query.
Should the motor be held by stalling it or should it be trying to turn? My 3 way BGMVSP-23 stalls in the mid position but is continually trying to turn in the CH only position and the motor is getting quite hot (about 50 degrees C)

Thanks in advance