Vaillant flow restrictor

[Scott_D]

Anyone else had complaints of poor hot flow on Vaillant combis?
They are restricted to the lpm that allows the boiler to give a 42 degree rise
24kw 8lpm
30kw 10lpm
It means the water is hot but the flow “isn’t as good as the old boiler”

 

[Harvest Fields]

Anyone else had complaints of poor hot flow on Vaillant combis?
They are restricted to the lpm that allows the boiler to give a 42 degree rise
24kw 8lpm
30kw 10lpm
It means the water is hot but the flow “isn’t as good as the old boiler”

This is why you end up fitting an 835 in place of an 30 kw old boiler in a 3 bed. As the old boiler probably did 13lpm and a 30 kw Vaillant will not do that. So you have to fit the 835 and range rate the heating.

 

[Scott_D]

This is why you end up fitting an 835 in place of an 30 kw old boiler in a 3 bed. As the old boiler probably did 13lpm and a 30 kw Vaillant will not do that. So you have to fit the 835 and range rate the heating.

It means the boiler costs more and needs a gas upgrade
It’s a shame you can’t remove the restrictor and fit one that allows a 35 degree rise

 

[Harvest Fields]

It means the boiler costs more and needs a gas upgrade
It’s a shame you can’t remove the restrictor and fit one that allows a 35 degree rise

That’s why it is important to check flow rates when upgrading boilers and not just banging in a direct replacement. Vaillant have a 15mm connection on the gas. I have only ever had to upgrade about 5 gas pipes in my time.

 

[ShaunCorbs]

Most boilers have restrictions stops too much flow going through the plate and giving warm water

Baxi in the tails
Worcester in the plate/ pipes to the plate
Vaillant in the iso valves
Etc

 

[Scott_D]

Most boilers have restrictions stops too much flow going through the plate and giving warm water

Baxi in the tails
Worcester in the plate/ pipes to the plate
Vaillant in the iso valves
Etc

Restricting to allow a 35degree rise is understandable.

 

[ShaunCorbs]

Restricting to allow a 35degree rise is understandable.

42 most are now starting to do especially on the lower kw as winter time there not getting as hot eg 35 degrees etc