Honeywell v4073a valve noise

[Bennachie]

Hello!

The aforementioned mid position valve has been replaced on an open vented, Y plan system with 22mm primaries and 8mm feeds to radiators from manifolds (I know). The system is clean and all radiators are new. Heating and DHW are fine, both work as required and provide required heat. However, if CH and DHW are on together, there is a significant 'thunk' from the valve when DHW is satisfied. This did not happen with the previous Honeywell valve (still going strong after 28 years) which was changed out as it seemed like the right thing to do as the system was being upgraded. GSR man fitted a new boiler (GW HSX) and a replacement Grundfos Alpha 2L 15-60 Pump (which, incidentally is not intelligent enough) to replace the 28 year old 15-50 which, was not quite man enough for the 28 year old Glow Worm Fuel Saver when the thermostat was turned right up.......

There is no 'balancing valve' in the DHW circuit, which is completely 22mm pipe.

I am assuming that the clunk is caused by unrestricted flow through the 22mm heating pipes slamming the honeywell ball closed as there is much more resistance in the heating circuit than there is in the DHW.

My question is therefore, is there a simple solution to this problem?
Will a valve swap solve the issue?
Should there be a 'balance' on the dhw circuit?

Many thanks

 

[Bennachie]

A week gone and loads of views but no one has come across this before?


Hmm.................

 

[ShaunCorbs]

there should be a bypass fitted, but haven't come across a mv that has a loud clunk as the parts inside eg the decider for hot water or heating or both is rubber so shouldnt clunk

bit of a long shot but could you post a vid up of it in clunk mode ?

 

[townfanjon]

Sorry I have only just seen this, as Shaun says .... Bypass is needed , the zone valves close slowly or should do .

 

[Bennachie]

Any idea why it should do it with a new valve but not with the old one? It is definitely slamming shut as you can make it do it by moving the valve manually off the seat and releasing. It also does it to a lesser degree with the pump not running and call for DHW as the valve is de-energised and springs back to DHW only..............

Many thanks to you two for replying, I was beginning to give up hope.........

 

[ShaunCorbs]

Any idea why it should do it with a new valve but not with the old one? It is definitely slamming shut as you can make it do it by moving the valve manually off the seat and releasing. It also does it to a lesser degree with the pump not running and call for DHW as the valve is de-energised and springs back to DHW only..............

Many thanks to you two for replying, I was beginning to give up hope.........

busy week

i see so its when the pump is still running and the motorized valve shuts eg no call for heating or hot water?

 

[townfanjon]

The odd post does go missing but now its back on the 'new posts' loads will see it lol

 

[doitmyself]

However, if CH and DHW are on together, there is a significant 'thunk' from the valve when DHW is satisfied. ...a replacement Grundfos Alpha 2L 15-60 Pump (which, incidentally is not intelligent enough)

So the clunk occurs when the valve goes from mid-position (CH and HW) to CH only? Do you get a clunk when CH is called by itself? (The valve needs to be set to the HW only position to check this: set timer to HW on; turn cylinder stat down; turn the complete system off and back on. Then turn CH on and room stat up.)

What setting is the Alpha pump on and why do you say it's not intelligent enough?

Did the installer balance the system after installing the new boiler and pump?

Which versions of the Fuelsaver and HSX?

 

[Bennachie]

System is balanced (I believe)
Was Fuelsaver 45ff is now Ultracom HSX18

1.
No CH, No DHW, no pump. CH is timed to come on. There is a slight, but noticable thunk as the spring return is released then pump and boiler fires.

2.
If both CH and DHW are called for, (or if one joins the other) the pump runs, boiler fires etc., etc. when DHW is satisfied a louder thunk happens as the valve is (I assume) slammed shut.

I acquired another valve body and have been comparing it with my old one and there are differences, no doubt in an effort to save money. However, the action of sealing the ball seems slightly different on the older one by allowing a progressive introduction of the surface of the ball to the metal seat. This could of course simply be the action of age.......

Alpha 2L 15-60 set on 3 as 2 is not man enough and causes kettling noises and none of the 'clever' PP settings prevent kettle.

 

[DirksPlumbing]

There would be an easy solution: get a balancing valve fitted.

The thud occurs by a high mass of water circulating at a high speed and suddenly getting stopped. 1 liter of water is 1kg mass. Water is non compressible.

The Alpha 2L is intelligent but unfortunately the design of the pipework was not at the same level. This pump can do a lot of things. But what you are asking for, you might be better off with a half inch Centerbrand miracle.

Sorry, had to do that . You need to slow down the flow of the coil to match the resistance of the rest of the system. As you use the pump in an uncontrolled mode you should have as well the aforementioned automatic bypass. This major difference in flow speed will cause further problems once the system needs to heat the house. During DHW heat up there will be likely little to no heat for the radiators und an unnecessary high return temperature causing cavitation and efficiency loss.

If the boiler "kettles" it simply has more heat available than it can get rid off. A half decent modern boiler will quickly modulate down. If there is cavitation even on low load then its time to call someone qualified. I had one case where a 40kW heat only boiler had been fitted to a brand new house. When I calculated the rads, there were roughly 10kW load. The boiler could modulate down to 12kW. I think that is said enough.

 

[DirksPlumbing]

By the way, at what flow temperature do you run your boiler? A lower temperature means less temperature on overshooting. But of course you need at least cylinder temperature +5K.

 

[DirksPlumbing]

System is balanced (I believe)
[Snip].

Please do correct yourself here. I hope the system is not balanced. To squeeze the water through DN6 and then still throttle the flow even further down does not make the slightest sense at all. Unless the system is not working anyway and you try to provide the customer with a solution until the problem is fixed.

Rule of thumb: do not balance microbore. Grundfos does do great webinars and courses regarding balancing for free.

The TRVs are the best balancing in such a system. All lock shields fully open.

 

[DirksPlumbing]

I assume the old setup had the pump switched by demand rather into the pump port on the boiler?

 

[Bennachie]

Demand

Thanks for your help. System runs at 68 degrees. House is warm, all rads are hot and DHW heats rapidly. Rads remain hot when both DHW and CH are on. System appears effective apart from the hammer on valve closing.
To alleviate the hammer I have programmed separate session times for CH and DHW temporarily.

 

[DirksPlumbing]

If you got the time just compare the return temperatures of the CH and the DHW on a normal system run. Your return temperature determines how much gain you have from condensation.

Of course not solely but mainly. You will struggle to cool your flue gases to 60 degree if you have 61 degree return.