Loft layout for Boiler, Hot water cylinder and expansion vessesl.

[jimmyhorns]

I am in the process of getting my loft ready for (and doing some of the fitting of) a multi-phase process. An extension is being undertaken and the current heating and hot water system is being significantly changed.

 

Currently we have an vented heating and hot water system, with heat coming from a regular 'heat only' boiler in the ground floor kitchen. An expansion / feed tank in the  middle of the loft for this system, a pump in the airing cupboard on the first floor on the opposite side of the house from the boiler. There is a expansion / feed tank (227 litres) for the hot water cylinder that sits in the airing cupboard.

 

The airing cupboard is going (it forms part of the new ensuite) and as a result we are swapping over to:

 

Unvented hot water cylinder in the loft (to replace the 227 litre e/f tank)

Unvented primary circuits on the central heating / hot water system, with the expansion vessel and filling point being in the loft.

 

Once this is done we will then be moving the boiler to the loft (or installing a new one, not sure yet) and moving the circulating pump and 3 way valve up in to the loft.

 

There appears to be only one sensible layout for the relative positions of these things in the loft. Mostly this is driven by where there is adequate support for the weight of the new unvented cylinder, and where the gas supply will be entering the loft. 

 

Having done the calcs, to allow for the 2x 45 form bends to get the gas pipe in through the soffit board and then onto a truss and then two further 90 degree form bends to get to the boiler,  in the planned 22mm pipe the maximum length is 5.5 metres. Once allowance is made for the drop down and out of the soffit (before it mates with 28mm pipe from the metre) this only gives me 5 metres of length to get to the boiler, both in the horizontal and vertical axis. The bends required to get into the loft make running 28mm through the loft a nightmare and I am keen to avoid this. 

 

I am hoping to have everything ready to go for the boiler fitting on this conversion for a gas safe fitter to come and do the soldering of the gas line, and then connection of the pre-installed flow and return feeds, and of course the installation of the flue. When I say everything ready to go, I mean all the pipe cut to size, with the appropriate bends etc (not soldered where joins are required).

 

Partly this is down to me wanting to do some of the work myself, but a great deal of it comes down to cost. There is limited budget for the extension, as with most things in life and I would prefer to be able to move the boiler rather than leave it where it is to save costs (the kitchen becomes a 'snug' room after the extension is done).

 

So I guess the point of the post is to 'sense check' where I am planning on the various bits being installed, because it's going to be a massive headache if all of the water side of this gets done, and then it turns out this is the only place where the boiler can be.

 

I have attached a couple of drawings of what is there now and what I am planning. The new boiler position would be just to the right of where the expansion vessel is now.

[TonyT]

Make the gas pipe 28mm...

[jimmyhorns]

3 minutes ago, TonyT said:

Make the gas pipe 28mm...

 

I can reach my proposed position with 28mm from the meter to just short of the soffit board and then 22mm from there to the boiler in my proposed position without any issue.

 

The issue is whether my proposed layout is any good!?

[PeterW]

Just get some Tracpipe and use that - you get better bends in it, and it’s dead easy to thread through everything. 
 

Your issue will be getting a tank up there at that size, and ironically you may want to go larger (they tend to be shorter ..!) and also look at the support you can get under the tank as ideally you want it spread across 5 trusses as a minimum. 
 

Also I’m confused as you say you have a full vented system but what is that expansion vessel connected to in the pictures ..?

[TonyT]

Make sure the area at the boiler is floored, with a light fitting for easy installation

 

plywood the back wall where the boiler will be, gives good fixings everywhere, make sure it sits on the floor that will help spread the load.

 

as Peter says make sure the tank is well supported, trac is a good idea too as it lets you complete the installation and the fitter only has to connect up either end, savings in labour to be had..

 

are you having 2 immersion as back ups?

top and bottom just in case problems with the gas supply/ boiler issue

 

make sure there is a metre in front of the boiler for servicing...

 

[Onoff]

@jimmyhorns, your tight for space loft reminded me of this thread that might be of interest:

 

 

[jimmyhorns]

13 hours ago, PeterW said:

Just get some Tracpipe and use that - you get better bends in it, and it’s dead easy to thread through everything. 
 

Your issue will be getting a tank up there at that size, and ironically you may want to go larger (they tend to be shorter ..!) and also look at the support you can get under the tank as ideally you want it spread across 5 trusses as a minimum. 
 

Also I’m confused as you say you have a full vented system but what is that expansion vessel connected to in the pictures ..?

 

Thanks Peter

 

I hadn't thought of Tracpipe as there is a significant external run (4m up from the meter box) on the outside wall of the house and didn't think this would be acceptable.... It would however allow the whole run to be done as one piece without any joins. I've just ordered 10m of the 28mm along with tape and fittings which should be completely future proof in terms of if we need a bigger new boiler.

 

I can get the tank in (just) at 530mm in diameter by removing the loft hatch (i fitted it with screws rather than nails about a decade ago 'just in case'). Its 1600mm in height. The current 227 litre tank is raised off the trusses by a jenga arrangement of 2x6's, presumably to give it some height (there are 4 levels). This spreads the load across 5 or 6 trusses, the end two of which are doubled up. This has been carrying the weight of the tank, and the heating circuits e/f tank for 40 years and looking at the total loading from the new system I will be about 30kg over this which will hopefully not be an issue, though with some of the wood I am removing I am likely to get to more like 20kg over or even closer to neutral.

 

The expansion vessel isnt actually connected to anything - I was just trying out the location for height and access and then realised I had better plan for the boiler now rather than later!

[jimmyhorns]

14 hours ago, TonyT said:

Make sure the area at the boiler is floored, with a light fitting for easy installation

 

plywood the back wall where the boiler will be, gives good fixings everywhere, make sure it sits on the floor that will help spread the load.

 

as Peter says make sure the tank is well supported, trac is a good idea too as it lets you complete the installation and the fitter only has to connect up either end, savings in labour to be had..

 

are you having 2 immersion as back ups?

top and bottom just in case problems with the gas supply/ boiler issue

 

make sure there is a metre in front of the boiler for servicing...

 

 

Thanks Tony

 

When there is reference to the area being floored, does the floor have to be flat and continuous. What I mean by this is that in the wider angle photo, if I floor the 'gaps' between the 2x6 going across the trusses, is it ok for the installer and later engineer to have to step over the remaining supports? There is 600mm between centers for the trusses, so presumably the metre in front needs to be the width of the boiler plus as much as I can leave?

 

There is a single immersion in the tank as a back-up and for frost protection and looking at the spec while this wont give us the luxury of 2 baths being filled simultaneously, its enough to get away with in a push.

[TonyT]

People like British Gas engineers may be reluctant??

 

as long as the flooring is secure, space for them to work adequately lit, I’m sure most would just crack on..  

 

check the boiler instructions as it will tell you what free area around the boiler you need to ensure compliance.

[Onoff]

Is a horizontal UVC something you've considered?

 

For example:

 

https://www.gledhill.net/products/alternative-energy/stainlesslite-horizontal/

[Ferdinand]

On 07/12/2020 at 12:23, jimmyhorns said:

 

Thanks Tony

 

When there is reference to the area being floored, does the floor have to be flat and continuous. What I mean by this is that in the wider angle photo, if I floor the 'gaps' between the 2x6 going across the trusses, is it ok for the installer and later engineer to have to step over the remaining supports? There is 600mm between centers for the trusses, so presumably the metre in front needs to be the width of the boiler plus as much as I can leave?

 

There is a single immersion in the tank as a back-up and for frost protection and looking at the spec while this wont give us the luxury of 2 baths being filled simultaneously, its enough to get away with in a push.

 

I bought a rental with the boiler in the loft several years ago, and there was no walkway to it - so may not be needed.

 

I put one in anyway with a moveable section of insulation over it, and a sign by the loft hatch saying where to look.

 

Personally I absolutely hate having it up there, and it will be coming downstairs when replaced.

 

F

[TonyT]

Reg 28  of the gas safety regulations basically says you have to have space to safely install and access equipment for maintenance.

manufacturers specific instructions will detail this advising what can be fixed to the left, right of it and other clearances that must be maintained.

 

I would be annoyed if I had to service a boiler in a loft and had nowhere to stand safely wouldn’t you?

 

 

[Ferdinand]

55 minutes ago, TonyT said:

Reg 28  of the gas safety regulations basically says you have to have space to safely install and access equipment for maintenance.

manufacturers specific instructions will detail this advising what can be fixed to the left, right of it and other clearances that must be maintained.

 

I would be annoyed if I had to service a boiler in a loft and had nowhere to stand safely wouldn’t you?

 

 

 

All plumbers have the grace of ballet-dancers and the altheticism of gymnasts. They can emboite along the joists, and split jump back.

 

Olga Korbut and Rusty Joiner could do it, so why not my gas engineer?

 

It's the next British Gas advertising campaign.