Heating Bangs when switching off.

[ShaunCorbs]

I would drain down and wack some x800 in the system for a week then drain it down again and fresh inhb

 

[Paul Cooksn]

I already did flush and the water ran clean. I opened all the bleed valves to get all the water out. The pump was old, dated year 2000 so it needed replacing anyway.

 

[Paul Cooksn]

Just updating again on this. I refitted the radiator and now the heating Bangs even more. Really am at a loss. Anybody with any further ideas.

 

[Frog67]

The fact that you have water flowing out the vent pipe when the system shuts down indicates you still have a fault, probably a blockage somewhere near the expansion pipe. You could try turning the speed on the pump down to its minimum to see if the noise reduces. Another thing to try would be to remove the rad again, empty it, refit, turn on the valves but don't bleed it. (it should act as an expansion vessel).
One thing i noticed looking at the pictures is the vent from the boiler looks like its running horizontal along the ceiling, so it may be possible that the system has an air lock.

 

[Frog67]

Forgot to say, that as you mentioned the amount of muck in the magnet suggests that the system needs a good clean.

 

[Paul Cooksn]

Forgot to say, that as you mentioned the amount of muck in the magnet suggests that the system needs a good clean.

Thanks for your advice. The pipe or pipes running across the garage ceiling are the flow and return to the boiler. The vent pipe is in the airing cupboard and goes about 18 inches abouve the header tank in the loft. When filling the heating back up after draining it doesn't bang, it's only when all the air is out the system so similar to your radiator test. Turning the pump down reduced the bang noise.

Cheers.

Paul.

 

[SavageW]

Got a picture of the new by-pass that’s been fitted ? Hard to tell from airing cupboard picture but is the open vent an cold feed teeing in just before pump

 

[Paul Cooksn]

Got a picture of the new by-pass that’s been fitted ? Hard to tell from airing cupboard picture but is the open vent an cold feed teeing in just before pump

 

[ShaunCorbs]

Where's the bypass valve all I see is a full bore ISO valve ?

 

[SavageW]

The valve put in on the by-pass looks like a ball fix turned 1/3 off have you tried opening this fully an seeing if this stops the banging
*shaun beat me to it,but that isn’t correct for a by-pass that’s why you still have the banging

 

[Paul Cooksn]

The plumber said it didn't need one, I thought it might and I asked again whether it needed to be 22mm. I can change it myself if you are able to advise what to get and where to put it. If the valve is fully open then yes it does stop it banging.

One question, I have lived in the house for 13 years without a single bang. Why would this start after removing the radiator.

 

[Paul Cooksn]

The valve put in on the by-pass looks like a ball fix turned 1/3 off have you tried opening this fully an seeing if this stops the banging
*shaun beat me to it,but that isn’t correct for a by-pass that’s why you still have the banging

The plumber said it didn't need one, I thought it might and I asked again whether it needed to be 22mm. I can change it myself if you are able to advise what to get and where to put it. If the valve is fully open then yes it does stop it banging.

One question, I have lived in the house for 13 years without a single bang. Why would this start after removing the radiator.

 

[SavageW]

I didn’t even pick up on that it was 15mm,that won’t help an then with the type of valve that will neither. You’ve said that with it fully open the banging stops.I could only say that since the 13years you’ve been there that the pipework /heatexchanger has become restricted.

 

[Paul Cooksn]

I didn’t even pick up on that it was 15mm,that won’t help an then with the type of valve that will neither. You’ve said that with it fully open the banging stops.I could only say that since the 13years you’ve been there that the pipework /heatexchanger has become restricted.

Cheers for your help. Could you tell me what valve I need and where it should go.
I assume the valve is operated by bar pressure

 

[SavageW]

bypass valve open vented system - Google pretraga ask your plumber who installed your by-pass to come back an rectify

 

[Paul Cooksn]

bypass valve open vented system - Google pretraga ask your plumber who installed your by-pass to come back an rectify

Your a star cheers. Is it in the right place above the valves

 

[Paul Cooksn]

One final question.

Should I fit the new 22mm auto bypass valve to replace what is there or should it go after the pump but before the motorised valves.

Thanks. Paul

 

[Last Plumber]

Has a Plumber put that in?

 

[Paul Cooksn]

Has a Plumber put that in?

Yes.

 

[Paul Cooksn]

Has a Plumber put that in?

Hi sorry couldn't reply properly earlier.

Yes following your previous advice a plumber did fit it, new pump, new valve and I fitted the magnaguard. It stopped for a few days but when the air was completely out of the system it started again. I questioned whether a 22mm auto bypass valve was required and he said this will do the same.
I am perfectly capable of fitting it myself but am not sure where to fit it. Do I install in the same place or before the valves but after the pump.

I even re installed the radiator and it bangs.
Cheers. Paul.

 

[Last Plumber]

It will do there if it is 22mm and automatic. I am presuming you have a 3 mtr min loop from boiler and back to boiler via by-pass?

 

[Paul Cooksn]

It will do there if it is 22mm and automatic. I am presuming you have a 3 mtr min loop from boiler and back to boiler via by-pass?

View attachment 31830

The distance from the boiler to the by pass is about ten meters. I will change the size of the plumbing and use solder joints as it looks a bit messy. I can fit it somewhere else if it works better. I would rather it be correct. Wish I had done the work myself.

Does the pressure have to be regulated by the pump flow speed. Cheers.

 

[Last Plumber]

One question, I have lived in the house for 13 years without a single bang. Why would this start after removing the radiator.

Because the Rad acted as a by-pass and you removed it!

 

[Last Plumber]

The distance from the boiler to the by pass is about ten meters. I will change the size of the plumbing and use solder joints as it looks a bit messy. I can fit it somewhere else if it works better. I would rather it be correct. Wish I had done the work myself.

Does the pressure have to be regulated by the pump flow speed. Cheers.

It's fine there, 22mm with either a straight valve like the one I showed you or an angled one where the elbow is

 

[Last Plumber]

Does the pressure have to be regulated by the pump flow speed. Cheers.

What speed is the pump on now?

 

[Paul Cooksn]

What speed is the pump on now?

Pump is on 2 as the system is quite large 12 rads.
Cheers.

 

[Last Plumber]

I

Pump is on 2 as the system is quite large 12 rads.
Cheers.

If it works well it's fine. You want them on the lowest setting that works and gives the right flow and return temps.

With the valve:-
screw it shut, turn on the heating and hot water so both Motorised valves are open and the pipes start to get hot. Slowly open the Auto by-pass 1/4 turn at a time, (a few seconds in between turning), until you feel hot water flow through the by-pass. Then close it back around a half turn.


That's the best explanation I can give on a Forum. I would be going to greater lengths to set things up and balance the system if I were doing this in person but it will do!

 

[Paul Cooksn]

I


If it works well it's fine. You want them on the lowest setting that works and gives the right flow and return temps.

With the valve:-
screw it shut, turn on the heating and hot water so both Motorised valves are open and the pipes start to get hot. Slowly open the Auto by-pass 1/4 turn at a time, (a few seconds in between turning), until you feel hot water flow through the by-pass. Then close it back around a half turn.


That's the best explanation I can give on a Forum. I would be going to greater lengths to set things up and balance the system if I were doing this in person but it will do!

Thanks I'll do it on Saturday and let you know how it goes.

Cheers.

 

[Last Plumber]

Thanks I'll do it on Saturday and let you know how it goes.

Cheers.

Please do come back and tell us how you went on.

 

[Paul Cooksn]

Please do come back and tell us how you went on.

Hi.

I fitted the valve where suggested and unfortunately it still bangs, perhaps even louder. I can't get water to run through the valve unless I restrict the hot water flow, even with it turned down to 0.1 bar, the lowest it will go.

Picture attached.

Cheers.

 

[Ric2013]

Does the light on the pump flash or stay solid?

 

[Paul Cooksn]

Does the light on the pump flash or stay solid?

Stays solid then switches off completely.

Cheers.

 

[Ric2013]

Okay. That's fine. If you were running it in flashing mode, then it would not be running fixed-speed, and the automatic bypass valve wouldn't be able to work as it should.

 

[Paul Cooksn]

Okay. That's fine. If you were running it in flashing mode, then it would not be running fixed-speed, and the automatic bypass valve wouldn't be able to work as it should.

I'm not sure it is. I can only get water to flow through when I restrict the flow on the hot water.

I would have thought 0.01 bar would be open all the time. Any suggestions.

Cheers.

 

[SavageW]

When you say restrict the flow on hot water,is this when the system is running eg demand from heating/hot water? The hot water coil should have a balancing valve on it that should be restricted (which from the pic you have one after the 2port) to stop the heat just whizzing around the coil and giving less to heating