HUGE complex calculation required ...........

[John M]

What do I set the bypass valve to ?

Is there a regular place where I should mount this ......... Or will any freakin' where do .... (Ideally accessible & yaddas)

 

[Gasguru]

Straight under the boiler will do if its only to reduce differential pressure on the TRV's, or further away (see the MI) if its to dissapate heat after boiler shutdown).

Normally close off all the TRVs and open up bypass to allow some flow. With the genuine Honey 145 I find you only need it on the lower settings with a 5 or 6m pump.

 

[John M]

Can I slap this on instead of using a heat dump in the hall ?

OPEN Locksheilds ?

 

[Agile]

As an aside, I recently fitted a cheaper Itallian ABV to a system with two zone valves tio cater for pump over run.

Problem is that its quite noisy compared with the very quiet boiler.

Any suggestions apart from covering with felt?

Tony

 

[doitall]

Anywhere after the pump and before any MVs.

To adjust turn the system on full then open the ABV till you get a flow, then turn it back one full turn.

Thats the rough way of doing it.

Fit binder points and DRV to measure the flow and adjust

 

[ChrisR]

Simple:
See boiler instrs to see what flow rate is required.
See pump curve to see what pump head will produce that.
See boiler instrs to determine head loss through boiler, then work out for pipe, at that flow rate.
Set ABV to pump head minus flow head losses.

 

[DavidJW]

Simple:
See boiler instrs to see what flow rate is required.
See pump curve to see what pump head will produce that.
See boiler instrs to determine head loss through boiler, then work out for pipe, at that flow rate.
Set ABV to pump head minus flow head losses.

Sorry to intrude on another conversation, but I have also been looking for instructions about setting an ABV and those of the manufacturers are not very helpful!

I can understand the first two lines above, but the third baffles me

What do I have to "work out for pipe"?

Would you explain please?

 

[gas4you]

HW off, Set abv to fully shut, no 6, close all trv's, turn on heating system, open abv until you can feel flow through bypass, then as DIA says turn back shut about 1/2 turn.

As taken from Honeywell MI's.

 

[chrishutt]

close all trv's ...open abv until you can feel flow through bypass, then ... turn back shut about 1/2 turn

Surely the ABV should be open if all TRVs are shut? If you set it to be closed at that point how is the minimum flow going to be accommodated?

 

[gas4you]

The abv only needs to open when all the trv's close, so by closing them you are simulating the pressure if they all shut.

The abv is then slowly opened until you feel the warm water flow through to the return, therefore you then know it is only going to open at that particular pressure.

Question that I have never heard categorically answered is, 'do you need an abv with a modulating pump?'

 

[chrishutt]

... then as DIA says turn back shut about 1/2 turn.

So what did you mean by that?

 

[gas4you]

Just quoting Honeywell MI's on this, I presume it is to make sure it will only ever open under definite 'all trv's' closed situations.