external prv for combi

[mutley racers]

Went to a job where the combi is in a basement hung in a basement flat with a stairwell right behind it. So the installer has come off the prv on boiler and gone right up above boiler to terminate above stairs. So it has no fall.

I remember reading on here that to put an external one in, I need to cap off boiler one and change return iso for a normal straight coupler and hey presto. Am I right about this chaps?

 

[Ermintrude]

Or tie the prv back into the adjacent heating pipe and then fit a remote one some where.

 

[mutley racers]

Or tie the prv back into the adjacent heating pipe and then fit a remote one some where.

Do you mean come of prv and pop it into the return? And keep the iso valve?

 

[Ermintrude]

Yes as if in basement will need to isolate to work on it. If it was upstairs I would say 3/4 female iron and no valve

 

[northcarr]

Just cap the prv on the boiler and put a prv upstairs then through a wall,just note it next to boiler prv that way any other engineer will know,certainty cheaper than a pump.

 

[Ermintrude]

Not permitted to have a valve between heat appliance and prv that would be the appliance isolator being removed or bypassed.

 

[Killy Bing]

Just cap the prv on the boiler and put a prv upstairs then through a wall,just note it next to boiler prv that way any other engineer will know,certainty cheaper than a pump.

Ohhh you're advocating disabling a manufafturers safety device???

lets bypass the o/h stat while we are at it....

 

[Barry98]

Went to a job where the combi is in a basement hung in a basement flat with a stairwell right behind it. So the installer has come off the prv on boiler and gone right up above boiler to terminate above stairs. So it has no fall.

I remember reading on here that to put an external one in, I need to cap off boiler one and change return iso for a normal straight coupler and hey presto. Am I right about this chaps?

What boiler is it I remember having this few years back and this manufacturer allowed it think it was a either a meter or 1.5 check with the manufacturer

 

[mutley racers]

Vailliant turbomax I believe

 

[diamondgas]

3 bar is 30m head ... raising the prv integrally a couple of meters won't effect the working of the valve so what regs does it come under? I know in my head its bad practice and something I wouldn't do, but what does it contravene? I for one would be interested in knowing

 

[mutley racers]

3 bar is 30m head ... raising the prv integrally a couple of meters won't effect the working of the valve so what regs does it come under? I know in my head its bad practice and something I wouldn't do, but what does it contravene? I for one would be interested in knowing

DItto

 

[Ermintrude]

Manufactures instructions as

 

[diamondgas]

Manufactures instructions as

But you only read them when you get stuck lol

 

[northcarr]

Killy I appreciate what you are saying re disabling the prv within the boiler but as I said as long as it is noted next to the boiler I can't see a real problem with it not ideal but a lot more cost effective,as long as the replacement is the same spec as the one within the boiler.

 

[Mike Jackson]

Killy I appreciate what you are saying re disabling the prv within the boiler but as I said as long as it is noted next to the boiler I can't see a real problem with it not ideal but a lot more cost effective,as long as the replacement is the same spec as the one within the boiler.

You can't disable a safety device and just make a note of it. The PRV must be before the isolating valves. The correct way is to tee into the return from the existing PRV and fit a 2.5 bar PRV at high level.

 

[Killy Bing]

Killy I appreciate what you are saying re disabling the prv within the boiler but as I said as long as it is noted next to the boiler I can't see a real problem with it not ideal but a lot more cost effective,as long as the replacement is the same spec as the one within the boiler.

As per mike jackson with bypassing to the return with the existing


you know you cant disable a safety device, no matter where you note it.

What happens when the note is removed or lost, next engineer comes along and reports you for it?

is it worth it.

 

[arran197]

Yes, prv MUST be teed back in to the return if a remote prv is fitted. End. The only time it would cause isolating the boiler an issue is if the prv passes badly. The prv will hold the water back, so you can work on the boiler.

 

[wattsie1987]

3 bar is 30m head ... raising the prv integrally a couple of meters won't effect the working of the valve so what regs does it come under? I know in my head its bad practice and something I wouldn't do, but what does it contravene? I for one would be interested in knowing

Prv discharges then pipework freezes. Prv attempts to discharge again later on but cant as pipe frozen???

 

[diamondgas]

Prv discharges then pipework freezes. Prv attempts to discharge again later on but cant as pipe frozen???

I've attended many a frozen PRV, a good handful at least. Installed perfectly correctly but passing slightly. They freeze at point of exit!

My post actually mentioned running the PRV internally.... At one time mi's would state that they had to terminate no more than 6" from ground level. That usually meant that a long length of 15mm copper was stuck onto the sides of walls, un-insulated!! I totally get the freezing idea ... My question is regards regulations and where does it state MUST NOT​? Just curious

 

[northcarr]

You can't disable a safety device and just make a note of it. The PRV must be before the isolating valves. The correct way is to tee into the return from the existing PRV and fit a 2.5 bar PRV at high level.

So what does that achieve by routing the existing prv into the return I can see it may look better but pointless.

 

[Ermintrude]

Because if you have isolating valves the prv can bypass them and get to the alternate prv by ch primaries. It's set lower to ensure that the boiler dosnt have 3 bar in it heating as no one wants a sealed steam boiler in their house!

 

[mutley racers]

Nice posts. Thanks guys. It is all clear now

 

[Ermintrude]

As mud or melted chocolate?

 

[mutley racers]

Mud I think

 

[lame plumber]

Prv discharges then pipework freezes. Prv attempts to discharge again later on but cant as pipe frozen???

if its discharged once why would it need to discharge again once the pressures dropped on a sealed system? not really an issue is it

 

[Ermintrude]

if its discharged once why would it need to discharge again once the pressures dropped on a sealed system? not really an issue is it

Oooooh you da man!

 

[Mike Jackson]

if its discharged once why would it need to discharge again once the pressures dropped on a sealed system? not really an issue is it

Vessel Lost it's charge pressure. PRV discharges system pressure drops so custard tops system up. Not that uncommon.

 

[mfgs]

Vessel Lost it's charge pressure. PRV discharges system pressure drops so custard tops system up. Not that uncommon.

Exactly what I was about to type out haha.

 

[buckley plumb]

Went to a job where the combi is in a basement hung in a basement flat with a stairwell right behind it. So the installer has come off the prv on boiler and gone right up above boiler to terminate above stairs. So it has no fall.

I remember reading on here that to put an external one in, I need to cap off boiler one and change return iso for a normal straight coupler and hey presto. Am I right about this chaps?

got the baxi and vaillant instructions if you pm me your email will send

 

[stratplus]

Has anyone ever fitted a prv on the primary return externally on a heat pump installation? You got me thinking now about freezing.