How big is your plant room?

[LnP]

I'm looking at our new build design and wondering how big the plant room should be. We currently have 2550x950 mm.

 

We're future proofing the house for an ASHP, but will probably initially install a gas boiler, depending on building regs and how the relative price of gas and electricity are looking at the time. So that means under floor heating with all the manifolds and a bigger DHW tank. There will need to be room for the ASHP gubbins. We will have MVHR, but that can go in the loft. Have I missed anything?

 

How big would you advise the plant room should be?

 

 

Thanks

 

 

Edited November 22, 2022 by LnP

[JohnMo]

ASHP, shouldn't require anymore gubbins than a gas boiler.  A monobloc heat pump will live outside - the gas boiler inside.  You can use the same cylinder for either gas or heat pump, as long as you get one with a heating coil sized for a heat pump.  Ideally you should operate the gas boiler exactly the same way as a heat pump this will ensure you are always condensing.  Allow for a buffer cylinder, 50L to 100L should be fine as long as you don't oversize the heat pump.  A buffer is worth specifying even with a gas boiler, to stop that cycling.

 

So plant room will have a cylinder, buffer and possibly a manifold, if the MVHR is being located elsewhere.  Your door sounds huge, mine all went in through a loft hatch.

[nod]

If you have the room A little wider won’t hurt 

We made our PR 12.5 x1200 and have gone bigger this time 

[Kelvin]

Ours is 3.6m x 1.2m. I’d say yours is too narrow. What I did is get the measurements for the plant and drew it in the room to get a feel for the space. 
 

Assuming it’s monobloc ASHP the exchanger is outside and the only thing inside is the hot water tank and associated components. You might have buffer cylinder too. Our MVHR is in the plant room too as we don’t have a loft. 

Edited November 22, 2022 by Kelvin

[Conor]

You'd want it at least 1200mm deep - 600mm for the cylinder etc and 600mm standing room. How will it be accessed? You could get away with narrower if you had sliding doors or something along the long side -that's what we originally planned in ours - plant room a partitioned off strip in the basement hallway. Would have been the same depth s the stairs and we'd have a couple sliding doors so it could all be accessed face-on. In the end a separate plant room was chosen as we have loads of room in the basement.

[crispy_wafer]

1.2m*1.8 ish basically just an annex off the utility with a door if seeing the cylinder ever bothers me, will only house the cylinder and manifolds for water distribution.  MVHR is up in the loft because I didnt fancy mucking about with 6" pipes between the pozi's.  Job, jobbed!  Heatpumps will be outside.

[Kelvin]

Now I’ve looked at your plans you’re probably ok at 950mm as you have double doors across most of the width to give you access. 

[PeterW]

Got all the manifolds, shower pump, controls, 300 litre tank and a 100 litre buffer with expansions into a 1600x800 plant room so it’s about how you plan it out.

[ProDave]

I allocated a 5M by 3M space (roof space above garage) as "plant room"

 

In reality very little endued up in there (now used as a workshop)

 

The only thing of any size in there is the MVHR unit and the distribution plenums. Other than that it's just a pump and some small control gear for the heating system.

 

The ASHP is outside (apart from the controls mentioned above) 

 

The DHW tank made no sense there as it would be too far from points of use, so that is not in an airing cupboard off the spare bedroom.  Following on from that the distribution manifold is in the ceiling void above the utility room accessed from a hatch, again to keep all the pipe runs as short as possible.

 

So how much plant room you actually need depends where it is and if it is suitable for everything together, or if the layout of the house favours a distributed layout of "plant"

[Kelvin]

Yes our plant room is designed to be quite central for this reason but it does mean all the MVHR ducting has to be threaded through the ceiling. 

[Nick Laslett]

How did people finish off their plant rooms? Flooring, walls etc. 

 

I have 2x ICF walls and 2x stud walls. Did you plaster the walls? Plywood instead of plasterboard?
 

I haven’t installed the UVC or MVHR yet. Bare concrete slab right now. 

[Happy Valley]

Our plant room is combined with the utility room - utility one side (washing machine, sink under 1000mm unit and spare fridge/freezer) and plant the other (hot water cylinder, heating manifolds/pipework and MVHR unit, circuit breakers. There is room for a cupboard and hanging coats etc. It's on the ground floor with one of the doors connecting to the garage

 

Two walls were ICF and two blockwork. We had them plastered and the screed floor is covered in LVT. 

 

Room is 3.9m max x 3m max 

[jack]

16 minutes ago, Nick Laslett said:

How did people finish off their plant rooms? Flooring, walls etc. 

 

Our plant room walls are Fermacell. Annoying to fit, but very strong, and allows some quite heavy things to be mounted to it without the need for a plywood backing. I think a single screw can take something like a 30 kg vertical load. I've never had anything move once screwed to Fermacell (we have it in some other places in the house too).

 

Floor is cheap cork tiles (on sale at Wickes when we bought them) over concrete.

 

Do think about having both heat and smoke detectors installed.

[JohnMo]

Ours is in an insulated airtight roof section, walls and ceiling are nice a shiny airtightness vapor control layer - heavy items are mounted on off cuts of 18mm ply.  Floor waterproof 22mm chip board.  Under that is 200mm of Rockwool Flexi.  Access through airtight insulated loft hatch with integrated stairs - all help keep noise away from the living space.

[Rick K]

On 23/11/2022 at 08:57, jack said:

 

Our plant room walls are Fermacell. Annoying to fit, but very strong, and allows some quite heavy things to be mounted to it without the need for a plywood backing. I think a single screw can take something like a 30 kg vertical load. I've never had anything move once screwed to Fermacell (we have it in some other places in the house too).

 

Floor is cheap cork tiles (on sale at Wickes when we bought them) over concrete.

 

Do think about having both heat and smoke detectors installed.

 

I think in Scotland alarms all have to be linked throughout dwelling. From what I understand this is also retrospective. I would expect England and Wales to follow. I think this is correct, someone might know more.

[Rick K]

Our proposed PR is 3.4m x 1.7m. Interesting the different finishings people have opted for. Never heard of Fermacell so will now look at that.

[jack]

41 minutes ago, Rick K said:

I think in Scotland alarms all have to be linked throughout dwelling. From what I understand this is also retrospective. I would expect England and Wales to follow. I think this is correct, someone might know more.

 

I meant think about installing both heat and smoke alarms, specifically in the plant room. I'm not sure whether either is compulsory, but it's a small price to pay for a bit of extra safety.

[tuftythesquirrel]

We are quite luck in the sense that we have an upstairs plant room that is about 53m² (9.5mx5.6m).

It was designed to be right in the centre of the house, so wiring, plumbing and MVHR runs are radial in nature, hopefully keeping the length of runs minimised.

The area was completely clear so I’ve created some skeletal  walls from unistrut, with traywork to carry the wiring, plumbing and ventilation. This saved drilling holes in the plastered walls, which is my airtight barrier and the architectural brickwork. Plus if you have to move anything, you aren’t left with an unsightly hole. I’ve also started to create some partition walls (out of unistrut). It also means you have access to both side to run cables etc.

I’ve only got the plumbing in so far, but it seems to be working out quite well (see pics). I don’t see why it wouldn’t  work out in a smaller area.

[LnP]

10 minutes ago, tuftythesquirrel said:

We are quite luck in the sense that we have an upstairs plant room that is about 53m² (9.5mx5.6m).

It was designed to be right in the centre of the house, so wiring, plumbing and MVHR runs are radial in nature, hopefully keeping the length of runs minimised.

The area was completely clear so I’ve created some skeletal  walls from unistrut, with traywork to carry the wiring, plumbing and ventilation. This saved drilling holes in the plastered walls, which is my airtight barrier and the architectural brickwork. Plus if you have to move anything, you aren’t left with an unsightly hole. I’ve also started to create some partition walls (out of unistrut). It also means you have access to both side to run cables etc.

I’ve only got the plumbing in so far, but it seems to be working out quite well (see pics). I don’t see why it wouldn’t  work out in a smaller area.

@tuftythesquirrelYour "plant room" looks amazing! You'll have to give guided tours, it's a work of art!

[Roys]

Looks proper, I do like a bit of unistrut

[tuftythesquirrel]

10 hours ago, LnP said:

Your "plant room" looks amazing! You'll have to give guided tours, it's a work of art!

Thanks, it's still a work in progress. I'll leave the tours for my wife - I prefer being on the tools ☺️

[Seren161]

Tufty’s plant room definitely looks the business..I definitely would go as big as is comfortable to. We had 1.8m x 2.7m and it has ended up a touch too snug because we originally did not plan for one and split our generous utility room to create ours. 
All our MVHR equipment, Solar PV set up and batteries, Hot water cylinders, Buffer cylinder, Water softener..blah blah..will be lucky to get a little space left over to put the rechargeable vacuum cleaners out of sight..

Fermacell sounds a brilliant idea for maximising wall placement… as does making sure that there are good heat smoke alarms installed .Earlier on in our design process ..researched Plant rooms as I had this same question and there was precious little info out there..Really informative thread! 

[JackofAll]

On 22/11/2022 at 12:03, PeterW said:

Got all the manifolds, shower pump, controls, 300 litre tank and a 100 litre buffer with expansions into a 1600x800 plant room so it’s about how you plan it out.

 

Hi @PeterW

Ours will not be much bigger, had hoped to get the Mhrv unit in and whatever bits required for solar but guess it would be too tight. Plan to put sliding doors on open side. 

[PeterW]

2 hours ago, JackofAll said:

Plan to put sliding doors on open side

 beware of using sliding doors - they are difficult to sound proof.

[JackofAll]

52 minutes ago, PeterW said:

 beware of using sliding doors - they are difficult to sound proof.

Seeing that the washing machine and dryer will be in utility would the noise be louder than either of those? With 3 teenagers in the house there's a wash on everyday, twice when bed clothes are done. Is the Mhrv unit noisy?