Converting a vented system to sealed

[rcflyers]

We have just had a new Worcester Bosch 24Ri boiler installed but I keep getting air in the radiators.
I asked the installation plumber and he suggested converting the system to a sealed system to eliminate the air.
I have 2 zone valves, one for the copper hot water cylinder coil and one for the radiators.

Am I correct in thinking I would need to fit the following:

An expansion vessel/tank
A fill loop with check valves to connect the mains water into the radiator circuit.
A pressure gauge
A pressure relief valve

Then I could remove the existing fill/expansion tank from the loft.

The fill loop and pressure gauge can go in the airing cupboard easily
The pressure relief valve would have to go in the garage by the boiler so it can be vented outside.
Would the expansion vessel work best in the garage or in the airing cupboard?

The only thing that worries me is can the existing plumbing take 3 bar of pressure?

Also, how big an expansion vessel do I need?
I have seen units ranging from 8 litres to hundreds of litres in size!
I live in a 4 bed detached house with 7 radiators and 2 heated towel rails.

Thanks for any advice.

 

[Onetap]

We have just had a new Worcester Bosch 24Ri boiler installed but I keep getting air in the radiators.
I asked the installation plumber and he suggested converting the system to a sealed system to eliminate the air.

Why did your previous boiler fail? Did thye radiators get air-locked on that?

It hasn't been installed properly and is not fit for purpose. The air will cause rapid corrosion of the radiators and sludge damage to the system. There could be a number of reasons why the air is getting into the system; I suspect he has suggested a sealed system because he knows it's pumping over and doesn't want to amend the existing system to stop it, at his cost.

Tell him to fix it or get someone competent to do so at his cost.

http://www.rwc.co.uk/products/heating-products/109-easifit-sealed-system-kit

 

[Nige F]

That`s a harsh reply - do you expect Gas Safe bods to be good pipework plumbers too

 

[hazetimesfive]

dont think you will be putting 3 bar in it..

 

[Onetap]

That`s a harsh reply - do you expect Gas Safe bods to be good pipework plumbers too

But of course, Nige.

It is a mediocre standard of technical competence one might reasonably expect from an installer.

Similarly, one might reasonably expect a competent installer to know that water freezes at 0 degC and discharging condenaste water into an exposed external drain will ............

Oh, hang on a moment. My reasonable expectometer seems to need recalibration.

 

[ianmcd]

An expansion vessel/tank
A fill loop with check valves to connect the mains water into the radiator circuit.
A pressure gauge
A pressure relief valve

all of these come as a kit, I call it a Brevco kit but think that is just a trade name havent installed one for a while, as a rule of thumb calculate 1L of expansion per radiator unless you have all huge double panel radiators most system boilers have 8L or 9 L expansion vessels installed as standard and it can be installed anywhere on the return pipework

 

[rcflyers]

The previous boiler was working ok but we wanted a more efficient one.
Thanks,
I don't think this regular boiler has any expansion tank fitted.

 

[Onetap]

The previous boiler was working ok but we wanted a more efficient one.
Thanks,
I don't think this regular boiler has any expansion tank fitted.

The air locking seems to be a problem introduced by fitting the new boiler, rather than a pre-existing problem with the heating system.

If the old boiler had gravity HW circulation and pumped CH, it is predictable that this would happen unless the system pipework was modified.

An open-vented heating system would have a feed & expansion cistern/tank in the loft.

A sealed system would have an expansion vessel, a sealed pressure vessel containing a diaphragm and an air space. The air is compressed when the water is heated because the water expands.

 

[rcflyers]

"If the old boiler had gravity HW circulation and pumped CH, it is predictable that this would happen unless the system pipework was modified."

The whole system is pumped.
It's an S plan layout.
If the air is being drawn in through the vent pipe above the header tank in the loft would it do any harm if I extended the vent pipe below the water level in the tank so it could not suck air in?

 

[Terry lambert]

With this boiler you could do a combined cold feed and open vent.


Make sure the open vent is between the boiler and pump.
Cap cold feed from tank
Connect a 22 mm tank connector to tank and fix the 22mm open vent.

You now have a semi sealed system that is much less likely to entrain air.

There are quite a few things that can cause air in the system.

In he manual it will tell you the tank should be a minimum height from the top of the boiler, the open vent should extend 450 above the tank

Did the installer have issues filling the system? Could be a partial blocked cold feed.

Is it pumping over at all? Pump setting too high ?

There is more but my fingers are starting to bleed

 

[Terry lambert]

I would hope that your installer was competent to know a basic s plan lay out.

Boiler, open vent, cold feed, pump, auto by-pass, motorised valves

 

[rcflyers]

Thanks Terry,

The 15mm and 22mm pipes from the loft tank are both in between the boiler and pump.
So, If I am understanding this correctly I blank off the 15mm feed from the tank, connect the 22mm pipe under the water level in the feed tank after having first removed the up and over swan neck part of the 22mm pipe?

 

[rcflyers]

Untitled

• rcflyers
• 18 Nov 2012
• 1

something like this?

 

[rcflyers]

I would hope that your installer was competent to know a basic s plan lay out.

Boiler, open vent, cold feed, pump, auto by-pass, motorised valves

Yes, the system is in that order although the feed and vent pipes are both connected to an Airjec device.

 

[rcflyers]

Can I just say that we only moved into this house in April, the only work the plumber has actually done is to fit the new boiler in the garage, he is not responsible for any other existing plumbing in the house.

This shows the pipe layout in the airing cupboard .

Ignore the arrows on the Airjec, some of them are wrong.

Untitled

• rcflyers
• 18 Nov 2012
• 1