Pipes violently banging on biomass installation

[BEC]

Hello there,
thanks for taking the time to read this. Bit of a tricky one I think. I got called to a biomass boiler installation about 2 years old (not mine) where the central heating pipes inside the house are banging when the water temp at the boiler gets to 40 odd degrees. It is a 40kW herz boiler and there is a 4000l (yes, that's 4 thousand!!!) buffer vessel which is obviously between the boiler and the central heating.
What's confusing me is that the banging only begins when the boiler itself heats up but I would have thought that the effects of any air/unsupported pipes etc. would comfortably be absorbed by the massive buffer vessel.
the customer has kept his old oil boiler which he is using while we come up with a solution. This boiler bypasses the buffer straight onto the central heating and he has had no problems with it.

If you've got any ideas on this please let me know cos it's got me stumped!
cheers
mike

 

[IDCHAPPY]

Sounds like it's kettling mate, sure it's only 40?

 

[tamz]

Sounds like a circulation problem.

 

[gassafe]

Depends how it's been piped up to allow the biomass & oil boiler to operate on the same system... Could be a faulty check valve or a pump / motor valve on the biomass side? 4000 litres seems big for any 40kw boiler lol??

 

[Unregistered]

Sounds like it's kettling mate, sure it's only 40?

Yeah, the customer said that it was at 40 (I wasn't actually there at the time) so that made me rule out kettling. I had wondered about a 3-way motorised valve between the flow and return on the biomass side which was buzzing in a strange way but I don't see why that would make such a violent shaking of the pipes. Can you tell me different?
Yes, it is 4000l. I don't know why it's so big but I don't think it's doing any harm, he's just got a massive buffer!

 

[MC_Bob]

Not kettling.
How many 3ports are on the back of the boiler. Should be two with a 4 tonne buffer. 35mm pipework.
Is one of them thermostatic or electric?
Thermo ones bang when they're :nono:.

 

[Dotty]

Bob, please read the forum rules regarding swearing.

 

[BEC]

There is just one 3-port on the back of the boiler and it's an electric

 

[MC_Bob]

Check it even opens. And at what point its bangin.

Sorry croppie its part of my nature

 

[Gray0689]

Depends how it's been piped up to allow the biomass & oil boiler to operate on the same system... Could be a faulty check valve or a pump / motor valve on the biomass side? 4000 litres seems big for any 40kw boiler lol??

4000 is way to big 2000 at most
What size expansion vessel is on system
How big is house

 

[MC_Bob]

4000 is way to big 2000 at most
What size expansion vessel is on system
How big is house

Lol why. Doesn't matter to his problem, just curious..

 

[Gray0689]

Lol why. Doesn't matter to his problem, just curious..

Don't Remember asking you

 

[MC_Bob]

Fella came onsite to ask for help. Your trying. I'm asking what direction your trying to help in.

So no, you didn't.

 

[Gray0689]

Again did I ask you the question
That problem could be caused by lots of factors
Start simple first

 

[MC_Bob]

Not by a larger buffer tank.
If vessel was bad, there'd be 500liters of water on his floor every time it turned on.
I don't know about the house bit.

And I said already, you didn't ask me. I was asking you. I'm trying to help the OP out.

Can't you work with others?

 

[Gray0689]

Yes I can
but seems you have an attitude
I asked the op the question
Rule of thumb would be 50 litres for every kw so buffer to big imo if expansion vessel to small and no safety valve
I've seen them capped plenty of times
Could be a huge pump on system for a small house set on max all underfloor actuators closed but pump wired wrong and running no bypass pipes badly clipped iron or sb clips can make a right rattle
So yes I do think my questions and I've plenty more are relevant

 

[MC_Bob]

Thanks. I'm asking so I can learn. Not to tread on your toes.
I think its specific to the biomass boiler otherwise he would have issues with the oil boiler running too.

Have a nice night.

 

[Gray0689]

Bio mass to buffer will have its own pump possibly a laddomat
Or just a esbe valve for back end protection

And oil boiler would also have its own pump
Then a pump from buffer to house

You wasn't asking to learn you was trying to be pedantic

 

[MC_Bob]

Don't get me wrong, I don't think your right, but I know that doesn't make me right

 

[Gray0689]

Don't get me wrong, I don't think your right, but I know that doesn't make me right

I didn't say I was right about anything I asked a question

 

[Billy Bob Bob]

Don't get me wrong, I don't think your right, but I know that doesn't make me right

FFS ,thats it both your handbags are being confiscated,stop squabbling ,the [pair of you or croppie will come and try to look you in the eye

 

[MC_Bob]

I've got a wardrobe of handbags though..

Edit: Dude chill out. Its the internet.

 

[Gray0689]

I've got a wardrobe of handbags though..

I'd say your right
And dummy's

 

[Gray0689]

I've got a wardrobe of handbags though..

Edit: Dude chill out. Its the internet.

And I still don't like you

 

[ashling]

Hi do you have any hydraulic separation between the biomass boiler, buffer and the Heating system.

Does the Customer have a plate heat exchanger or is it piped direct, to the heating system.

 

[ashling]

Hi does the system have any hydraulic separation. Is the heating piped direct or does the customer have a plate heat exchanger.

 

[BEC]

Hi do you have any hydraulic separation between the biomass boiler, buffer and the Heating system.

Does the Customer have a plate heat exchanger or is it piped direct, to the heating system.

Hi Ashling,

no, there is no hydraulic separation. Just goes boiler-buffer-house with pump on the house side. Upon closer inspection of this system I have seem that the 3-port is not operating correctly so I am going to change that out for a thermostatic and see what happens.

thanks for your help everyone who contributed! Will let you know what happened.

 

[MC_Bob]

Nice one.

 

[BEC]

Ok, so eventually got to the bottom of the problem after sitting for about 4 hours waiting for the whole boiler to heat up! The three-port on the boiler to buffer side was faulty and wasn't diverting heat back into the return. This was causing the boiler temp to rise above 95 and then ( this is what was throwing me) the automatic coolant kicked in firing water through the internal heat exchanger to prevent overheating. This caused the cold water pipes in the house to shake which was what raised the issue in the first place.

swapped out the three port, boiler doing nicely and no more banging pipes. Thanks for your help people!

 

[MC_Bob]

Ah great.