Central Heating Port Valve Water Hammer

[RK_London]

Some background. Went from vented to unvented system 5yrs ago when I added an extension to the house. I have 15 radiators and underfloor heating. Boiler fitted was a Vaillant Ecotec plus 637. It's a 3 port valve system for heating, hot water and underfloor heating. Water cylinder is 290 litres.

Only issue I have left that is has been dragging on for 5yrs is what looks like water hammer when the heating motorised port valve closes when boiler goes into pump over run. So get this regular banging all day long.

I've checked to make sure the direction of the valve is fitted right way (green arrows in 3rd picture below) and it looks ok. Not sure what the issue is. I've attached some pictures of my heating system.

Any help appreciated. Thanks.

 

[cross thread]

Have you an auto by pass ?

 

[CBW]

Have you an auto by pass ?

In between the flow and motorised valve

 

[CBW]

Are you sure about the valves being the right way? Judging by the dimple on the Honeywell 2 port valves, the one by the cylinder appears to be on wrong/different than the other 2. I also think you have an Splan plus system as opposed to a 3 port valve

 

[RK_London]

Are you sure about the valves being the right way? Judging by the dimple on the Honeywell 2 port valves, the one by the cylinder appears to be on wrong/different than the other 2. I also think you have an Splan plus system as opposed to a 3 port valve

You are right - it is an S plan plus system - I meant to say I have 3 ports valves.

I have checked again - looks ok. I've attached pictures for each.

First one is valve by cylinder

Second one is valve for flow heating

third is valve for underfloor heating.

 

[Johntheo5]

Does it happen when any one of the zone valves shut?
Is the ABV installed correctly, what make/setting index is it on?,

 

[RK_London]

Does it happen when any one of the zone valves shut?
Is the ABV installed correctly, what make/setting index is it on?,

Only the central heating valve . It is interesting you are asking the question about the bypass valve installation. Boiler initially installed without external bypass because plumber said this boiler had an internal bypass. When I got a Vaillant engineer to do my annual service he wasn't happy there was no external bypass so go the plumber back and he fitted it. Picture below - not sure of the make and have not touched setting since plumber installed bypass valve.

 

[Johntheo5]

That setting is way too low at 0.1, 1M, it must be recirculating at all times?, just screw it clockwise to say setting 0.45 and test for hammer by opening/closing the CH.

 

[RK_London]

You are right - it is circulating at all times. Will adjust.

Thank you for your help.

 

[Mister Banks]

You are right - it is circulating at all times. Will adjust.

Thank you for your help.

Let us know if this fixes the issue as i am having the same water hammer problem on my heating a Honeywell ABV, the difference is that on my setup the hammer doesn't happen very time the heating valve closes.

 

[RK_London]

Let us know if this fixes the issue as i am having the same water hammer problem on my heating a Honeywell ABV, the difference is that on my setup the hammer doesn't happen very time the heating valve closes.

ok - will test over a few days

 

[RK_London]

Tested for a two days and there is a slight improvement but problem still persists - banging in pipes around the house which begins when port valve closes and boiler goes into pump over run. Banging lasts for a few minutes then repeats end of the next heating cycle.

Is there a way to test if CH port valve is ok? Or maybe after 5yrs of living with this problem, pipes have become abit loose and are now banging against joists?

 

[Mister Banks]

Thanks for the up date. My problem is a bit different, I only get hammer when the heating has been on for quite a while and is very hot , the CH 2 port valve closes and I get a single hammer/knock sound somewhere in the pipework.

 

[Johntheo5]

Tested for a two days and there is a slight improvement but problem still persists - banging in pipes around the house which begins when port valve closes and boiler goes into pump over run. Banging lasts for a few minutes then repeats end of the next heating cycle.

Is there a way to test if CH port valve is ok? Or maybe after 5yrs of living with this problem, pipes have become abit loose and are now banging against joists?

If you are absolutely sure that the CH is orientated correctly then maybe just worth replacing it.

 

[RK_London]

How do you check if CH orientated correctly?