plant room Plant room Design

[openthegate]

Hi all - The combined wisdom on here is unrivalled and I have picked up countless tips - ever so useful. So I thought I would pick your brains!

 

We are still getting plans ready for the planning application. The house is going to be built into the side of a hill (with a gap of around 1.2m between the house
and retaining wall.) It works out best for the views (and light) to have an upside down house with bedrooms on the ground floor and living areas on the first floor - 
where the front door will open out to the roadside. 

 

The light on the North/West sides is quite limited and it makes sense to put the plant and utility spaces here. 
Attached is an my initial thought on the layout of the plant/utility space and where to place any ducts - the plan is go for a fabric first 
approach which includes ensuring all the external connections go through the slab rather through the walls to reduce the cold bridging. 

 

My rational for the layout is:
ASHP on the north façade - placed the un-vented hot water cylinder much further into the centre of the house so the bath/shower/washing machine are all close 
to minimise the hot water pipe lengths. 

By moving this to the Utility space I though it would then be a sensible option to have all the water centric kit (washing machine/dryer/UHC/UFH) separate from the electrical kit.

Placed the inverter externally to avoid over heating (as suggested by Jeremy H) - it is not in sun light and there is a cover over as well. 

 

Is the layout sensible - any suggestions - all thoughts gratefully received. 

 

Thank you.

[Bozza]

Just two general recommendations.

 

1.  If your ASHP/heating system has or is likely to have internal pumps, they can be noisy, so don’t have your plant room adjacent to, or below bedrooms etc.  if they must be consider acoustic insulation.  Don’t have MVHR so don’t know if the units are noisy or not.  
 

2.  Consider future proofing your house by designing in the capacity to easily run additional electrics or pipe work  from the plant room to outside, perhaps by access hatches, empty conduit or whatever.    At this stage the costs are tiny/nominal.  Whether electric vehicles, back up generator, wind turbine,  personal nuclear reactor, personal drone landing site, alien laser defence system.  Just never know what the future tech or energy supply demands may be.  We’ve had to retrofit a generator hook up due to supply issues due to weather.   Would have cost pennies to do so at time of build.  

[Gus Potter]

17 minutes ago, openthegate said:

 

 

Hello @openthegate

 

Welcome to Buildhub.

 

I can see you have spent a good bit of time crafting your post, it's appreciated by me. There is loads of info on BH, it's a friendly place. To provide a bit of context and further encouragement. I'm "in the trade" but I always learn something new when I log in. There are a load of other folk that are like minded, we want to share what we know and in return we want folk to reciprocate. This is a good site as folk will tell you.. I did this wrong and here is what went well and this is how I did it.

 

Ok to kick off I've copied and pasted you post and added some initial coment inline with your text.

 

We are still getting plans ready for the planning application. The house is going to be built into the side of a hill (with a gap of around 1.2m between the house
and retaining wall.) It works out best for the views (and light) to have an upside down house with bedrooms on the ground floor and living areas on the first floor - 
where the front door will open out to the roadside. 

Like the idea of the upside down.

 

The light on the North/West sides is quite limited and it makes sense to put the plant and utility spaces here. 

Agree but if using ASHP would you get more bang for you buck by facing into the warm prevailing wind from the Southerly direction? You want to extract warm air from outside.. is it a good idea to site it in the coldest spot?
Attached is an my initial thought on the layout of the plant/utility space and where to place any ducts - the plan is go for a fabric first 
approach which includes ensuring all the external connections go through the slab rather through the walls to reduce the cold bridging. 

In principle I can see what your are doing. But in buildability terms when the pressure is on and the rainjis puring down the less slab penetrations you have the better.

 

My rational for the layout is:
ASHP on the north façade - placed the un-vented hot water cylinder much further into the centre of the house so the bath/shower/washing machine are all close 
to minimise the hot water pipe lengths. 

By moving this to the Utility space I though it would then be a sensible option to have all the water centric kit (washing machine/dryer/UHC/UFH) separate from the electrical kit.

Placed the inverter externally to avoid over heating (as suggested by Jeremy H) - it is not in sun light and there is a cover over as well.

 

If you post some elevations and a few more drawings you'll get a lot more response as it means folk don't have to second guess you.. it's much more efficient this way and then we can get down to the nitty gritty which is chipping to help you achieve a good buildable design at a sensible / affordable cost. In return you need to share what you learn... so all the folk an BH learn, it's not a bad deal and the Mods (who have worn every tea shirt going pretty much) keep everyone on the right track.

 

 

 

 

 

 

 

 

[PNAmble]

We are in the build phase of an upside down house, with a retaining wall (gabion) to the south and a metre gap to our timber frame! 
 

our SE got us to minimise the slab connections due to DPM/ Gas membrane sealing as we initially wanted power via the slab. Instead we are building a kiosk out side the plant room to push electric and data services back to; and have an external consumer board and network switch which all external needs feed from.  Minimising future penetrations.  The initial penetrations will be ducted/sealed with grommets and filled. 
 

we’ve got water in and out via the slab, as we wanted to be able to isolate external taps from the plant room so no t’s off the main water feed. 
 

I’d put the battery outside if possible; I wouldn’t want a battery fire inside. 
 

our ASHP /battery/inverter/kiosk are all on the east side next to the plant room.
 

finally our Nuaire design for MVHR insisted on intake and exhaust being on the same side of the building, and to fresh air not to the rear ‘passage’. (Which will be covered by a patio) 
 

we having living space above the plant room (kitchen) and bedroom next door which will have additional sound insulation.  The plant room is 8mx1.5m.

 

 

 

[JohnMo]

My view is keep things simple. Never really seen the point of ducted ASHP pipes, when you can simply come through the wall then clip pipe to wall and insulate very easily.

 

You seem to devote two rooms to plant, consider merging into one room.

 

Do the MVHR inlet and outlet on the same wall otherwise you encourage a mismatch of pressures and unbalanced flows depending on the wind. Consider a combined directional grille, if it simplifies duct routing.

 

You need drainage for the MVHR unit as well.

 

Not sure why you need a radiator in a plant room, when you have the UFH manifold and cylinder in same room.

 

Consider bringing inverter inside

 

Don't buy into the put the ASHP on the south side, they consume so much air it's ambient air temp they see and half their life its dark anyway.

[PNAmble]

1 hour ago, JohnMo said:

You need drainage for the MVHR unit as well

We’ve actually put a full floor drain in our plant room in addition to the MVHR drain just in case, and will allow us to easily drain systems if ever required.  

[Kelvin]

The reason we did duo ducted pipe for the ASHP was because there wasn’t an easy route from the pump to the plant room due to full height windows and doors in the way. We also put in a few extra ducts to future proof getting power to different parts of the plot. The mistake I made is not making it wide enough. It’s 3.4m long but only 1.1m wide.  I could do with an extra 200mm-300mm so yours is the perfect size. I quite like the two separate rooms. If you have the space them why not. Gives you an extra wall to hang things off. 

Edited December 16, 2023 by Kelvin

[Dreadnaught]

MVHR: ensure the intake and exhaust are on the same face of the building so they are exposed to even wind pressure.

[Iceverge]

On 15/12/2023 at 23:28, openthegate said:

ASHP on the north façade

 

Like @JohnMosays that's fine, it moves so much air that unless you can move it to the south of France the north side will make little difference. 

 

On 15/12/2023 at 23:28, openthegate said:

placed the un-vented hot water cylinder much further into the centre of the house so the bath/shower/washing machine are all close 
to minimise the hot water pipe lengths. 

 

Kitchen tap (run in 15mm) is the one you need to consider. Run basins in 10mm pipe and you'll have tiny dead legs. Washing machines almost exclusively use cold only feeds nowadays. 

 

On 15/12/2023 at 23:28, openthegate said:

moving this to the Utility space I though it would then be a sensible option to have all the water centric kit (washing machine/dryer/UHC/UFH) separate from the electrical kit.

 

I wouldn't consider this vital but would ensure that any leaks could drain via floor level drain. 

 

UVC will need a tundish and discharge. 

A pull up drying rack is always nice. 

 

External MVHR ducts can be noisy so consider this. 

 

What is your planned construction type? 

 

 

 

[openthegate]

Many thanks for the super suggestions  - taken a number on board and attached a revision of the plant room plus included the ground floor plan to give a bit of context of positioning. 
(still waiting for elevations from the architect so cant show those).

 

@PNAmble - sounds like our builds are quite similar! - our kitchen is also above the plant room. What are you doing for heating(UFH/radiators?) on each floor.

 

MVHR input/output placed on the same wall to keep air pressure equalised.
ASHP  moved further East to allow space for MVHR intake. Positioning on the southern side is not an option (too close to the bedrooms), although it seems that there is no real noticeable difference in ambient air temperatures (locating on south side v north).

 

Unvented HWC (HWC) - moved close to the ASHP and run pipes in the space rather in a slab via a long duct - simpler and easier to change in the future should the need arise.
My initial thought was place the HWC as close as possible to the bath/showers in order to shorten pipe runs but energy expert Dave Hilton ( https://www.homebuilding.co.uk/advice/air-source-heat-pump-positioning ) maintains distance from the manifold/HWC is key.
A bit of conundrum, so going for a compromise and will place the manifold/HWC to be roughly equidistant between the ASAP and bath/showers. 

 

Combined the two rooms into one room but retained an internal door - I think it feels better to keep the sink well away from the electrics. 

 

Inverter - retained to be outside the thermal area - it is out of the sun and weather , my understanding is it will (hopefully) last a bit longer working in a cooler environment 
and avoids having the extra heat internally in the summer. 

 

Battery - retained internally, I get the concern over the potential fire hazard - in (hopefully never) event of a fire then it will kick off the fire alarm and the sprinklers which you will not get quite so easily if located on the outside wall. 

 

Using Kiosk alongside the plant room is an interesting idea to reduce slab duct connections - will look into that.

[openthegate]

21 hours ago, Iceverge said:

Kitchen tap (run in 15mm) is the one you need to consider. Run basins in 10mm pipe and you'll have tiny dead legs. Washing machines almost exclusively use cold only feeds nowadays.

That is interesting - the kitchen sink is directly above the proposed location of the HWC so should be ideal. I hadn't thought about using 10mm but that makes really good sense. 

Yes it is irksome you can not easily get hot filled washing machines - apparently a means of cutting costs rather than anything to do with economy. Although I did come cross some from EBAC https://www.ebac.com/washing-machines/features the other day (and made in Britain as well)

21 hours ago, Iceverge said:

What is your planned construction type? 

 

Timber frame - Twin stud with 300mm breathable insulation in the walls. Aiming to get to passive house levels of insulation/air tightness etc. (although I don't think it is worth all the effort and costs of actually getting certified)

[PNAmble]

51 minutes ago, openthegate said:

@PNAmble - sounds like our builds are quite similar! - our kitchen is also above the plant room. What are you doing for heating(UFH/radiators?) on each floor.

Although we have a slab (insulation above) due to being upside down - master bed / en-suite also on FF , 3 bed rooms GF - we’ve  gone ASHP and radiators.  We are building to Passivhaus Standards and airtightness but due to North facing and views  will can only get to approx 14w/m2. (House 207 m2) So we aren’t certifying. 
 

radiators running at 35/30 at -4 on a single zone but TRVs in the downstairs bedrooms to enable guests to step down if required. No radiator in Master Bed.  Electric Towel rails in 2 en-suite and bathroom.   ASHP (5kw) with no buffer / 300l OSO UVC
 

As designed EPC currently sitting at 96 (A). 

[Mike]

1 hour ago, openthegate said:

it is irksome you can not easily get hot filled washing machines - apparently a means of cutting costs rather than anything to do with economy

It's because modern washing machines use much less water. If they draw what they need from a hot pipe, that's often not enough for the hot water to actually reach the machine - you're starting with cold anyway, while the hot water in the pipe goes cold.