Pressure relief drain problem

[bigstu82]

Hi,

I've got a combi boiler with sealed heating circuit which has just been temporarily condemned following a boiler service, because the previous owner of the property (or whoever built the extension on the house for him) has done a bit of DIY plumbing.

The original pressure relief pipe would have exited the bathroom below the roofline of the new extension, about 4" below the bottom of the boiler. So they've used plastic right-angle connectors, and fashioned a "U" with the pipe going back up, and out through the wall about 6" above the bottom of the boiler. And the pipe that goes outside then isn't bent back in on itself so it's facing the wall. So as I understand it, it's an epic fail when it comes to building regs.

It looks like I've got 3 options as I understand it:

1. run a pretty fat pipe about 6 meters sideways through my bedroom (which will look awful)
2. raise the existing boiler (Ideal Mini) by about a foot (preferred if it's cheap)
3. get a new boiler installed (are Combi's really worth it...?)

Anybody have any thoughts on this, including how much (ballpark) it's likely to cost? Furthermore, anyone have any thoughts about whether I'd have a claim against the previous owner or the local council (who signed off the building inspection for the extension)?

All comments appreciated!

Thanks,

Stu

 

[grahamgas]

Any chance of a few pics?

 

[Centralheatking]

Yup, do some pics and we will sort you out

centralheatking

 

[bigstu82]

Cheers guys, I'll take some and get them uploaded this evening.

 

[AWheating]

you could possible blank the boilers pressure relief pipe or pipe it back into the system and then fit another pressure relief valve on another part of the system where its easy to get it to a safe position outside. possible off radiator pipework on an external wall. This would be alot less work and cheaper than lifting the boiler.

i would suggest phoning the manufacture and asking if they allow it to be done and how the require you to deal with the boilers prv. Ask your gas safe engineer to ask them.

welcome to the forum.

 

[bigstu82]

OK, they're not great photos, but let me know if you need any more specifics:

1. Bottom of boiler - copper pipe with plastic bends on the right is the pressure relief pipe. You can see where the pipe used to exit - that's now into a roof cavity. The existing pipe could probably exit an inch lower at most, given where the roof of the extension comes to.


2. Top of boiler - more than enough room to move it up a foot if needed...? It's in an enclosed full-height cupboard in the bathroom.

 

[Nostrum]

As AWheating said, providing the manufacturer allows, you could tee off the return pipework under the boiler and take a length of pipe up the side of the boiler. Fit the PRV at the top and exit out beside flue (assuming the flue terminate outside!)

Normally you fit a 2.5bar PRV to replace the 3 bar on the boiler. Some manufacturers sell this as an option, Baxi's part number is 5121379. I don't recall Ideal doing it though although there is no reason why as the principle is exactly the same. Might want to put an airvent on as well.

 

[Gary71]

I doubt a manufacture will put anything on paper as they would be responsible if it ever went pear shaped(slim chance I know) and they don't like moving a way from MI.

If you cap the blow off and fit another one elsewhere you will have to remove the isolation valve(s) from the boiler to stop the boiler from being isolated from the blow off, if you repipe the blow off into the system you risk being reported again by someone who doesn't understand basic plumbing and these things can turn in to a ****ing competion .

 

[bigstu82]

As AWheating said, providing the manufacturer allows, you could tee off the return pipework under the boiler and take a length of pipe up the side of the boiler. Fit the PRV at the top and exit out beside flue (assuming the flue terminate outside!)

Normally you fit a 2.5bar PRV to replace the 3 bar on the boiler. Some manufacturers sell this as an option, Baxi's part number is 5121379. I don't recall Ideal doing it though although there is no reason why as the principle is exactly the same. Might want to put an airvent on as well.

OK, so just to clarify, the manual for the boiler's here (can't do a proper link as I'm a newbie):

http www idealheating com/downloads/manuals/mini_is32.pdf

On Page 11 is the systematic diagram of the boiler - item 10 is the PRV? So I'm guessing that the "output" side of this valve has been soldered onto the original pipe that drops out of the boiler? And what you're suggesting is to get someone to (with Ideal's blessing) take the valve off, and, say, run a pipe from where the valve was down, across, and up the side of the boiler, then add a new PRV onto the end of that, and take the "output" side of that valve out of the house in accordance with building regs - so the pipe which has a "U" in it is then constantly full of hot water (i.e. is part of the sealed system, isn't open to the environment), can't freeze or breed legionella, and will only vent externally if - God forbid - the pressure goes over 2.5 bar?

What's the deal with the air vent? Just replace a standard brick with an air brick from outside into the cupboard, or something more? I think (presume) it's got one of those "co-axial" flues on it, and the CO figures on the annual test were well in the safe range - is it needed, or is a co-axial flue sufficient?

Thanks :shades_smile:

 

[bigstu82]

I doubt a manufacture will put anything on paper as they would be responsible if it ever went pear shaped(slim chance I know) and they don't like moving a way from MI.

If you cap the blow off and fit another one elsewhere you will have to remove the isolation valve(s) from the boiler to stop the boiler from being isolated from the blow off, if you repipe the blow off into the system you risk being reported again by someone who doesn't understand basic plumbing and these things can turn in to a ****ing competion .

Fair enough on point one.

As for point two, I'd have to make sure it was me at home when it gets serviced in future, not my missus who prefers fluffy kittens to pipes and wires...

 

[Nostrum]

Hi bigstu82

Heres a picture



The new PRV is exiting out the wall by the flue (assuming it is terminated outside after the extension!)

The existing PRV stays in, hence the new PRV having a lower rating (2.5 bar)

Air vent to release air in the vertical pipework, not knock a hole in your wall!

You should ask ideal first but this is a recognised method, baxi call it a secondary remote pressure relief safety valve or similar. Pretty sure vaillant offer it as well, and all the boilers works on the same principle in this instance so theoretically the boiler make/model is irrelevant. That said you should always go by manufacturers instruction......

 

[bigstu82]

Hi bigstu82

Heres a picture

The new PRV is exiting out the wall by the flue (assuming it is terminated outside after the extension!)

The existing PRV stays in, hence the new PRV having a lower rating (2.5 bar)

Air vent to release air in the vertical pipework, not knock a hole in your wall!

You should ask ideal first but this is a recognised method, baxi call it a secondary remote pressure relief safety valve or similar. Pretty sure vaillant offer it as well, and all the boilers works on the same principle in this instance so theoretically the boiler make/model is irrelevant. That said you should always go by manufacturers instruction......

Thanks for the picture, that makes sense - does the air vent have some clever trickery inside it to stop pressurised water getting out (path of least resistance and all that)?

If you wouldn't mind, as a rough idea, what would the cost of parts be (to the nearest £25 would be fine), and what would a reasonable labour effort look like? Couple of hours (presume the heating would have to be drained and refilled?), or more like a half/full day?

Thanks 🙂

 

[Nostrum]

Say £40-50 for the bits and 3 hours labour would cover it at a guess I reckon.