Return Bypass Valve

[Fenko]

Hi all

Can someone please advise how i would set a bypass valve when installing it onto the flow and return. The boiler i am looking at installing does not have one built into it.

I need a minimum flow rate of 2.5 l/m

Any help much appreciated.

 

[D_Hailsham]

Need more info!

Which boiler?
Which pump?

 

[Fenko]

Hi thanks for responding so quickly.

it is a glow worm betacome 30 i do not know the exact pump model im afraid.

 

[D_Hailsham]

it is a glow worm betacom 30 i do not know the exact pump model im afraid.

OK That's a combi boiler, so the pump is built in.

Where did you get the figure of 2.5 litres/min from?

 

[Fenko]

the user manaul states that this is the minimum

 

[picasso]

the instructions I have for the betacom 30 shows it has a built in bypass, do you have a gc number for the boiler you are looking at ?

 

[D_Hailsham]

the user manual states that this is the minimum

Do you mean this bit (it's actually in the Installation Manual)?

5.10 Water Pressure
To obtain the best hot water performance from your boiler it is suggested that the cold water supply to the boiler is the first draw off from the incoming mains supply.

NOTE: The boiler will not operate unless there is a minimum pressure of 0.25 bar (3.6 Ibf/in2) with a flow rate of 2.5 l/min.

That is the minimum flow rate of the cold water coming into the house. It refers to the Hot Water side of the boiler, nothing to do with the Central Heating side. The boiler will not run if the flow rate and pressure are below the set limits. so you won't get any hot water.

The boiler does require an Automatic Bypass Valve on the heating circuit; but this should have been installed and adjusted when the boiler was installed.

 

[Fenko]

the boilers gc number is 47-019-09.

i am fitting the pipework myself and the boiler engineer is coming on sat to commission it.

sorry for the confussion but it is the central heating that requires the arv but i have never fit one before. i thought the boiler i purchsaed had an inbuilt one but this apparantely is not the case.

on my previous properties i have carried out the pipework and my family friend commissions it for me. he has never had too fit an automatic bypass before and as such is not much help. My confusion comes about as the manual states that a minimum flow rate is required.

If it helps there the property is a 3 bed bungalow with 8 radiators and about 80 meters of pipe work.

 

[D_Hailsham]

the instructions I have for the betacom 30 shows it has a built in bypass, do you have a gc number for the boiler you are looking at ?

And the instructions I have say that a bypass has to be provided! (GC 47-019-08 and 47-019-09)

What's the GC number in your manual?

 

[Fenko]

the same gc number. i called glow worm today who advised that one has to be fitted!!!!!!!

 

[picasso]

the number I have is 47-019-05 so it looks like an older set of instructions than you have, I wonder why they removed the abv

 

[Fenko]

no idea, but it is doing my head in. any suggestions on how to set up the bypass valve?

 

[D_Hailsham]

The by-pass goes between flow and return (make sure the arrow points from flow to return). Leave a minimum of 1 metre pipe (each side) between boiler and valve.

The normal way of adjusting is as follows:

Close the ABV
Set all TRVs to Max
Run the boiler at full load until it reaches temperature.
Slowly open the ABV until the pipe on the exit side feels hot.
Close the ABV one turn.

There are more "scientific" ways of adjusting, but it requires expensive equipment which most domestic installers do not own.

 

[Fenko]

really appreciate your help. thanks.