Non-return valve for condensate pipe

[Sponge]

The condensate pipe for my boiler has been connected to an outside drain pipe shared with a toilet and hand-basin. (I'll dig out a picture.) A while ago an NPower engineer (fixing another problem) mentioned there should be a non-return valve installed.

My dad popped into Plumb Centre this afternoon and they suggested one of these.

It's on order, but not paid for. Will it do the job?

Untitled

• Sponge
• 17 Feb 2014
• 1

Only picture to hand at the moment. Condensate on right, basin waste in the middle and the toilet to left, nearly out of picture.

 

[Dan Robinson]

Not had to ft one in all the years I've been fitting condensing boilers.

 

[Richardthe3rd]

The condensate pipe for my boiler has been connected to an outside pipe. A while ago an NPower engineer (fixing another problem) mentioned there should be a non-return valve installed.

My dad popped into Plumb Centre this afternoon and they suggested one of these.

It's on order, but not paid for. Will it do the job?[/url]

Why would you need a non-return valve? Sounds a bit daft?

 

[Sponge]

Edited OP to add more information.

He said it was required because if there was a blockage, sewage from the toilet or basin could come up the pipe and into the boiler.

 

[ScottishGasMan]

You would use this in the case where its not an outside drain pipe, is it infact a rainwater downpipe you mean?

In that case there is a significant risk of during heavy rainfall the downpipe not removing the rainwater fast enough and the water backing up the condensate pipe and flooding the boiler (very pricey)

However a non return valve is far from the best soloution. If you can route the pipe to be correctly terminated indoors into a suitable drain, then I would suggest an "Airbreak" on the pipe outside would be the best option, ie the condensate pipe outside sits into a bigger pipe but with a gap around it, this way if water backs up, it will spill out, outside the building while still allowing the boiler to expell its waste condensate.

 

[Sponge]

I've added a picture to the OP.

The pipe it is connected to doesn't directly take rain water. However, it does ultimately tee into the underground drain that does.

I did consider an airbreak, as you describe, but in it's current configuration it would allow foul air from the sewer to escape.

 

[Richardthe3rd]

You would use this in the case where its not an outside drain pipe, is it infact a rainwater downpipe you mean?

In that case there is a significant risk of during heavy rainfall the downpipe not removing the rainwater fast enough and the water backing up the condensate pipe and flooding the boiler (very pricey)

However a non return valve is far from the best soloution. If you can route the pipe to be correctly terminated indoors into a suitable drain, then I would suggest an "Airbreak" on the pipe outside would be the best option, ie the condensate pipe outside sits into a bigger pipe but with a gap around it, this way if water backs up, it will spill out, outside the building while still allowing the boiler to expell its waste condensate.

Fitting condensate pipes into rainwater pipes is no longer recommended SGM.
If it's connected into a SVP & it chocked, chances are it would 'spill over' the WC before getting as high as the boiler, so still no requirement for a NRV.

It does look like a 21.5mm pipe, which is too small for external pipe work. It should be increased to as least 36mm for any external pipe.

 

[Dan Robinson]

Is the pipe on the left connected to a basin or bath?

If so then an nrv on the boiler is pointless.

Mine you this is an N POWER engineer we're talking about here. Hardly a rocket scientist.

 

[ScottishGasMan]

Fitting condensate pipes into rainwater pipes is no longer recommended SGM

Thats not new, Its never been recommended to terminate into a rainwater only pipe. Why I said it should be terminated correctly indoors if possible, However it does happen and if it was fitted like that then an air gap is the best way to protect the boiler.

BUt you are correct, if theres sinks/toilets on the same pipe at a lower level then the chances are that they would overflow before water would get a chance to reach up to the boiler.

 

[Sponge]

Pipe on left (actually the middle if you count toilet waste on far left) is the waste for a small, hand-basin.

One of the things I was considering was the potential for a blockage to cause the basin to empty up into the boiler. But I guess the relative heights would mean that's unlikely? The basin would overflow first? (Eg if tap is left running.)

I guess I could try removing the condensate pipe from the waste pipe and let it 'hang-loose' (create an air-break) and see how it goes, i.e. if it starts to smell?

None of this was worrying me up until 3 days ago when a blockage in the drain at the front of my property caused the downstairs toilet to nearly empty into the basin. It's cleared now, but it could happen again.

 

[ScottishGasMan]

One of the things I was considering was the potential for a blockage to cause the basin to empty up into the boiler.

If the boilers above the height of the basin then thats not going to happen.

If you really want to have an airbreak outside just fit a trap under it. The point of the trap is to stop smells comming back up. But you really dont look like you need to worrie about it

 

[Tipper]

One of the things I was considering was the potential for a blockage to cause the basin to empty up into the boiler.

If the boilers above the height of the basin then thats not going to happen.

If you really want to have an airbreak outside just fit a trap under it. The point of the trap is to stop smells comming back up. But you really dont look like you need to worrie about it

Surely a trap would freeze no matter what size it is?