Is this allowed??

megawatt · 7 Sep 2007

Bottom line is that manufacturers installation instructions are written with a purpose ... To ensure that their product operates as expected.

If you install it against their recommendations you do so at your own risk AND invalidate the product warranty.

megawatt · 7 Sep 2007

Apparently some manufacturers recomend terminating into a 10 gallon tank internally instead of taking the PRV pipe up!!!!

Who?

sambotc · 7 Sep 2007

Not sure think it may have been ideal?

Was informed a few months back by my boss, all our job's get inspected through the warmfront scheme and this has been passed before, the inspector's are extremly hot on current reg's too , more so than the majority of installers i reckon!

We have fitted a few PRV pipe run's which run up into the loft space and out facsia boards if the boile ris in the middle of a house on a vertical flue with awkward runs (chipboard etc) some of these have had issues which required the manufacturers to attend and none have been pulled up as an un suitable installation (all vaillant ecotec 824's)

IMO it's another grey area which i think is acceptable provided the pipe is lagged and a drain off s fitted underneath. Not to sure on the 10 gallon idea though!

Sam

megawatt · 7 Sep 2007

I think your boss may have been pulling your chain

I'm guessing that the next one will be ... "Just nip down to the stores and get me a 6" length of umbilical cord"

sambotc · 7 Sep 2007

lol no mate, i'm 7 years past that stage of replacing the bubble in the level !

Seriously this is how we have been reccommended to terminate blow off's if not fitting a vaillant and can't terminate PRV with a pipe without going upwards.. crazy IMO

brian30 · 7 Sep 2007

I've spoken to the installer. He said that it is not against the regs to use the same hole as the flue for the 'bloe-off'. He also said that Vaillant do not object if no other method is available.

I said the boiler was 'At Risk' and he just laughed at me saying it would never reach the stage of 'not to current standard'

However , he has reluctantly agreed to come back and drill a hole below the boiler. we shall see.....

undercover · 7 Sep 2007

mehran said:
if every thing else is all right then i would forgive him this.

So if you came across a few of these you would look the other way???

chrishutt · 8 Sep 2007

The PRV is a necessary safety device on modern boilers and must be able to work properly. An uphill running discharge pipe could well cause a blockage of the PRV outlet by the accumulation of hard scale from a small leakage and subsequent evaporation of the water. It would be foolish to really on the supposed annual service to maintain the PRV in working order.

Even if there was a drain-off point it would not prevent the above happening unless left permanently open, in which case the drain-off point would become the default discharge point and you're back with the need to accommodate the discharge at that level. Where an external discharge at low level really cannot be arranged then I'd go for an internal discharge into a drain or failing that the tank option.

Doctor Drivel · 8 Sep 2007

chrishutt said:
The PRV is a necessary safety device on modern boilers and must be able to work properly. An uphill running discharge pipe could well cause a blockage of the PRV outlet by the accumulation of hard scale from a small leakage and subsequent evaporation of the water. It would be foolish to really on the supposed annual service to maintain the PRV in working order.

Even if there was a drain-off point it would not prevent the above happening unless left permanently open, in which case the drain-off point would become the default discharge point and you're back with the need to accommodate the discharge at that level. Where an external discharge at low level really cannot be arranged then I'd go for an internal discharge into a drain or failing that the tank option.

I see no problems in running the PRV pipe upwards into the loft and out via the facia boards.

Your concern about scale blocking the upward pipe can be overcome by using 22mm on this run. The pipe would need to be lagged in the loft and running down all the way to the outside air.

Scale accumulating in a CH system PRV pipe to the point it blocks "may" occur. However the likelihood would be virtually nil. The CH system has inhibitor in it. Pressure drops the CH would be noticed and rectified.

Onetap · 8 Sep 2007

Doctor Drivel said:
Your concern about scale blocking the upward pipe can be overcome by using 22mm on this run. The pipe would need to be lagged in the loft and running down all the way to the outside air.

Scale accumulating in a CH system PRV pipe to the point it blocks "may" occur. However the likelihood would be virtually nil. The CH system has inhibitor in it. Pressure drops the CH would be noticed and rectified.

Dangerous nonsense, Drivel, as is usual for you. Utter drivel, in fact. Chrishutt is right.

The PRV is usually hot, so small water leaks evaporate and the dissolved solids are deposited around the PRV outlet. Increasing the pipe size won't affect this. The inhibitors usually in the CH are corrosion inhibitors; they do not remove the dissolved solids, they add to the TDS if anything. They won't affect the deposition of scale.

Given a long-standing drip (like your good self

) the PRV can become concreted shut by the limescale deposits. This is one of the reasons a boiler service and a service of an unvented water heater is supposed to include opening the PRVs to discharge at full bore.

megawatt · 8 Sep 2007

Doctor Drivel wrote:

I see no problems in running the PRV pipe upwards into the loft and out via the facia boards.

Your concern about scale blocking the upward pipe can be overcome by using 22mm on this run. The pipe would need to be lagged in the loft and running down all the way to the outside air.

Scale accumulating in a CH system PRV pipe to the point it blocks "may" occur. However the likelihood would be virtually nil. The CH system has inhibitor in it. Pressure drops the CH would be noticed and rectified.

I think we must assume that Doc Drivel actually has a sense of humour and is having a laugh here as, even by his standards, this one tops the bill

If he's not he may as well advise the OP to run the PRV discharge through the impulse drive plasma conduit to ensure that it does not interfere with the warp drive dilithium chamber matrix.

Doc D ... This is a joke ... Only better than yours

undercover · 8 Sep 2007

so anyway. If you came across one of these installs on a service or gsi, what would you class it as??

Gasguru · 8 Sep 2007

Down to manufacturer. I came across a Vaillant T'max Plus in an airing cupboard. PRV vent went up and across roofspace into gutter. They told me it was just NCS. We also see plenty of boilers where the PRV isn't even plumbed in again just NCS.

You could always plumb in an additional 3 Bar safety valve off the flow pipe elsewhere in the property where it was easy to terminate.

Ok so the boiler might be isolated on its flow/return valves AND the boiler PRV blocked but thats extremely unlikely scenario.

On the other hand the old Chaffoteaux Flexiflame 140 had flow and return isolating valves fitted as standard on the boiler. However no PRV valve was fitted internaly on the boiler. I wonder how many went bang after the valves were left closed after service work.

chrishutt · 8 Sep 2007

Gasguru said:
Ok so the boiler might be isolated on its flow/return valves AND the boiler PRV blocked but thats extremely unlikely scenario.

But the PRV is there to guard against extremely unlikely scenarios. I would regard plugging off of the PRV as a serious fault, even if there was another PRV elsewhere but with isolating valves between it and the boiler.

However your suggestion has reminded me of something that occurred to me before. The boiler PRV could be removed and replaced with a pipe rising to a higher level (without any valves in it of course) and a PRV then fitted to the end of the pipe. The boiler isolating valves would not then interrupt the route to the PRV.

In theory any excess pressure would be just as able to operate the higher level PRV as the normally positioned one (except in as far as the pressure reduces slightly with height). However I don't suppose for one minute that any boiler manufacturer would agree to such a modification so it's just a theoretical idea.

Gasguru · 8 Sep 2007

Problem is most PRV's fitted to boilers are an O ring fitment to a plastic manifold so there's no way to replumb it; and they are are often stuck at the back - look at that junk Greenstar Junior for a fine example.

If Atag can vent their PRV into the condensate drain then its only manufacturers being lazy and not wanting to have their boilers type approved to do the same. Do Atag insist the condensate must be PP? ABS and even PVC (to a certain extent) would not cope with the heat from a sustained high temp. discharge.

At one time Chaffoteaux were providing a short lenght of clear tube to connect between the PRV and the wall pipework on the Britonys - maybe it never actually complied (the filling loops on Vaillants don't comply with water regs either).

I'd start by banning all the carp filling loops - 99% don't comply (they rely on the installer adding a valve on the heating side). Since that never gets done the loops stay connected increasing the chance of letby. Then stop the manufacturures putting the vessel schraider valve in an inaccessible place preventing re-charging on a more regular basis.

diynot

If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.

Select the supplier or trade you require, enter your location to begin your search.

Are you a trade or supplier? You can create your listing free at DIYnot Local

Is this allowed??

Doctor Drivel

Similar threads