Plant Room Cupboard Plans

[MortarThePoint]

I've just ordered my ASHP & Cylinder package and am progressing my planning out of the Plant Room / Cupboard. The house design leaves a small room 1m x 2.6m for the following:

• DHW cylinder (ASHP): has a reasonably small footprint 575mm circle), though will no doubt have pipes all over the outside. Plan to leave extra 200mm all round. It is very tall, ~1800mm.
• DHW and cold water manifolds
• ASHP controls: Mitsubishi Ecodan. hopefully doesn't take up much space
• UFH primary pump and filters: I am going with a single large pump pressure driving a 3 manifold system. If I get issues, I can later add pump(s) to manifold(s), but no more space needed in Plant Room.
• UFH manifold: 4 port, 3 used. Plus controller.
• Electrics CU: 3-phase connection. This will be many way as I am having lots of circuits. I will also have a feed to the garage, which may be in a separate CU box. I guess it could end up as actually being 3 CUs, one for each phase where the phases are slit House / ASHP / Garage.
• Lighting control: a metal cabinet housing relays and control circuitry for the lights
• Battery bank: Potential to add this later. Server rack style. May choose to have it outside the house (e.g. garage or meter kiosk)
• Forgotten something?

Rough layouts below.

 

Walls & Floor Finish: Before the ASHP and DHW cylinder work can start, I need to decide what I am doing about the walls and the floor. They are currently bare blockwork and screed respectively.

 

For the walls I see three options:

1. As a minimum, I would seal the blockwork with Passive Purple for airtightness
2. Wet plaster the walls and paint
3. Simple tile

 

As for the floor, I see four options:

1. Leave as bare screed
2. Seal with a paint (like garage floor paint)
3. Simple tile
4. Tank and create some form of sump around the DHW cylinder. Would need a drain provision though

 

What have others done with their plant rooms?

 

 

[TerryE]

If you look at my blog you will see that my "plant room" is a (IIRC) 1.4m × 0.7m cupboard off our ground-floor toilet in our utility, the cupboard is separated by bi-fold doors that are normally closed but can also easily be removed entirely if full access is needed.  This all works well because I use 2×SunAmp PV units for my DHW.  This might give you some ideas.  Also @Nickfromwalesmany posts and advice here.  But some general comments:

• Maintenance access is essential.  I think you will find access to your DHW problematic.
• Don't forget your thermal calcs.  Parasitic DHW losses will turn this into a hot room.
• You haven't got many potable HW/CW manifold ports.  You want one per end attachment.  Sharing just isn't worth.  It is worth provisioning a couple of spares during design.  Move them nearer to the ceiling.  You will get more usable wall space.
• Water Softener?  Well worth fitting.
• Network / control racking?

What is your rationale for a combined ASHP/DHW system? We have separate resistive heated SunAmps.  Based on our actual HW use we would never get a payback for the extra complexity / hassle of one of these units.  Also remember that like most mechanical / compressor based systems, you might expect a 10-year working like if you are lucky.   Also if your main heating is water-base UFH then the flow temp should be ~35°C or less.  At this temp, an external monoblock ASHP should deliver an effective CoP of 4.

 

Oh, the pleasures and heartache of detailed design 🙂

 

 

 

Edited January 25, 2023 by TerryE

[Nickfromwales]

As long as the cyl stat and immersion are facing front, you’d be ok to bury the UVC in that ‘deep’ afaic, plus it looks like you have planned spacings to allow its retrospective extraction ( should ever become necessary ). Just make sure the cylinder does NOT use a sacrificial anode. 
For the UFH, how are you going to manage the differing temp requirements at each of the manifolds? A pumped brach Will only allow manipulation for the flow temp at source, and is not a good idea IMO, especially if one is on an upper floor?

[TerryE]

I assumed from the OP that it was the tank element of this unit (or similar model variant)

 

[Wil]

Our of interest, what’s the issue with sacrificial anodes as I have one in my UVC?

[MortarThePoint]

4 minutes ago, Wil said:

Our of interest, what’s the issue with sacrificial anodes as I have one in my UVC?

@Nickfromwales I guess it's the fact it's sacrificial and so wears out.

[Gone West]

4 minutes ago, Wil said:

Our of interest, what’s the issue with sacrificial anodes as I have one in my UVC?

As I said in another thread, anodes are fitted in enamalled steel tanks to prevent corrosion. The anode has to be removed for inspection at intervals and to do that the tank needs draining down to below the anode so it can be removed.

[MortarThePoint]

3 hours ago, Nickfromwales said:

Just make sure the cylinder does NOT use a sacrificial anode. 

It's a stainless steel cylinder so is that only relevant to copper cylinders?

 

10 minutes ago, TerryE said:

I assumed from the OP that it was the tank element of this unit (or similar model variant)

It's not going to be the official Mitsubishi one as there have been issues with supply.

 

Here's a thread on the cylinder:

But this is the datasheet:

[MortarThePoint]

2 minutes ago, Gone West said:

As I said in another thread, anodes are fitted in enamalled steel tanks to prevent corrosion.

 

Just now, MortarThePoint said:

It's a stainless steel cylinder so is that only relevant to copper cylinders?

 

Sorry, cross post. Is it not relevant to Stainless Steel though?

[Gone West]

Just now, MortarThePoint said:

 

 

Sorry, cross post. Is it not relevant to Stainless Steel though?

I would have thought it would have to be poor quality stainless steel if it was likely to corrode.

[MortarThePoint]

4 hours ago, TerryE said:

If you look at my blog you will see that my "plant room" is a (IIRC) 1.4m × 0.7m cupboard off our ground-floor toilet in our utility, the cupboard is separated by bi-fold doors that are normally closed but can also easily be removed entirely if full access is needed.  This all works well because I use 2×SunAmp PV units for my DHW.  This might give you some ideas.  Also @Nickfromwalesmany posts and advice here.  But some general comments:

• Maintenance access is essential.  I think you will find access to your DHW problematic.
• Don't forget your thermal calcs.  Parasitic DHW losses will turn this into a hot room.
• You haven't got many potable HW/CW manifold ports.  You want one per end attachment.  Sharing just isn't worth.  It is worth provisioning a couple of spares during design.  Move them nearer to the ceiling.  You will get more usable wall space.
• Water Softener?  Well worth fitting.
• Network / control racking?

What is your rationale for a combined ASHP/DHW system? We have separate resistive heated SunAmps.  Based on our actual HW use we would never get a payback for the extra complexity / hassle of one of these units.  Also remember that like most mechanical / compressor based systems, you might expect a 10-year working like if you are lucky.   Also if your main heating is water-base UFH then the flow temp should be ~35°C or less.  At this temp, an external monoblock ASHP should deliver an effective CoP of 4.

 

Oh, the pleasures and heartache of detailed design 🙂

 

• I was hoping that most of the stuff that would need access on the cylinder would fit on the front 120 degrees of the cylinder and have reasonable access. The plan was for the tank to go in before the wall is put up, but that tempts the installer to put something somewhere difficult.
• I am planning to fit a computer fan (120mm) to blow air out of the cupboard. They push about 90m3/h = 0.025m3/s and the heat capacity of air is around 1kJ/m3K. That means a 120mm computer fan can remove 0.025m3/s * 1kJ/m3K * 10K = 0.25kW with the cupboard 10C above the neighbouring room's temperature. The cylinders loss figure is about a third of that, so I should be OK (hopefully). There will be loss from the UFH too, but I could always add another fan.
• Cold manifold is one feed per room that uses water (all 15mm), garage and outside tap. DHW manifold is 10mm to 4 basins (3 bathrooms, 1 loo), 15mm to 3 showers* and 1 bath, 15mm to Kitchen, 15mm to Utility, 2 spare. Feels like adding a spare or two to the cold. Note: two of the showers are about 6m run from the manifold, the third is about a 15m run and (*) actually shared with a bath which will mostly be used more as the children grow up so waiting for hot isn't too bad. I have run the numbers on this before and they looked OK (10 seconds per 15m run at 10l/min shower, pure hot).
• I keep hearing people say I should have a Water Softener, but have never liked how the water 'feels' or tastes with them. I'm near Cambridge, so water is hard but not mega. I expect shower TMVs are the main risks with this so keeping them accessible (one through a hatch in the wall) and the other two are on shower bar so readily replaceable. We've had the same kettle with this water for ages, but do use a Brita filter (which gets replaced very infrequently).
• Network rack is going under the stairs with the other GF UFH manifold (toasty, so another venting computer fan or two is likely).

I'm far from Passive Haus standards so have to have a boiler/ASHP and so makes sense to use it to heat the water. I do wonder if I might regret not having a secondary tank coil, but don't currently have plans for anything that could use it. Possible future PV could be hooked up to this tank's immersion heater I presume.

 

Without the experience, I have to think it through ahead of time rather than rely on instinct. Many a time have I stood on site staring at something wondering what 'the right way to do it' is. Equally, sometimes you just have to get it done and move on.

 

[Wil]

 

1 hour ago, MortarThePoint said:

 

 

Sorry, cross post. Is it not relevant to Stainless Steel though?

Thanks, Cool Energy sent me an anode with my stainless steel tank so I installed it.. might just be wasting my electricity but it has a little control box which indicates as and when it wears out. 

 

Sorry for thread hijack.

[TerryE]

8 hours ago, MortarThePoint said:

Cold manifold is one feed per room that uses water

I don't understand your rationale here.  We have one run per appliance fitting, so for example our bathroom has 3  cold feeds (toilet, bath, basin) and 2 hot.; our ensuites ditto but shower instead of bath.  At @Nickfromwales suggestion we used Hep2O for all radial plumbing.  The pipe is relatively cheap and there are no hidden joints so the only real chance of a leak is if a pipe is directly holed, but it this case every fixing is separately isolatable at the manifold.  We layed out our house so that most plumbed rooms backed onto a central core so that most runs were short and it was a lot more convenient for us to run each pipe run direct to the fitting. I did all of the copper-work and soldering for the service cupboard, and Jan and I split the rest between us, with me usually acting as the labourer.  The pipe runs were pretty direct in within the ecoJiost space and only a short vertical run up the service cavity to each fitting.  We've got a kitchen, utility, bathroom and 3 ensuites but doing the pipe runs was a relatively small part of the total job.  Still doing this all ourselves meant that we saved a lot of labour costs and did everything to the quality we wanted.

 

If you have only one feed to your bathroom, say, then you need to have an accessible mini-manifold hidden somewhere in the bathroom and then take local runs to the appliances. This can be a PITA to run if the fitting isn't directly adjacent to the mini manifold.   The pipe costs about £1.50/m in coils, so using a per room manifold approach might has saved us maybe £10 per room.  Just not worth the hassle and extra fittings and plumbing.

 

See other examples on the forum for this type of installation.  Nick has posted some lovely examples.

 

8 hours ago, MortarThePoint said:

I keep hearing people say I should have a Water Softener, but have never liked how the water 'feels' or tastes with them.

 

Having got used to ours, I would never go back to not having one. 

 

We use soft water for everything other than cold drinking water.  It makes better tea and coffee, since the Ca and Mg salts in the hard water sediment out a lot of the nice flavour molecules (that's what forms the scum on a cup of tea if you use unsoftened water.  The change isn't really noticable either way for other cooking.  We keep a jug of cold water and a few sparkling water (Sodastream) in the fridge which I top up with a large jug drawn from the one tap that is plumbed to the hard side of the softener.

 

The main advantage of the soft water  is no tide marks on the whiteware and glass screens and no scaling on cookware and kettles; also no scaling on your HW cylinder and TMVs that are in a lot of appliances and feed to the manifold, so everything is maintenance free for far longer. 

 

8 hours ago, MortarThePoint said:

Without the experience, I have to think it through ahead of time rather than rely on instinct.

 

Researching  other self-builders experiences here on the forum and on similar resources might help.   It certainly saved my bacon quite a few times on our build, and my time doing this proved to be time well spent. 

 

Anyway best of luck on your journey. 😊

Edited January 26, 2023 by TerryE

[MortarThePoint]

7 hours ago, TerryE said:

I don't understand your rationale here.

I'll have to remind myself which I decided against individual pipes per appliance. On thing I don't like about it is the shear number of pipes I have to pass through a cavity wall which currently doesn't have holes in it for the pipes. If the local manifold is accessible, you don't end up with many more connections than without a local manifold. Consider for example a 3 appliance bathroom (shower, loo, basin) The connections are as follows

• Local manifold: at main manifold, 4no. at local manifold, 3no. at appliances --> 8 TOTAL
• No local manifold: 3no. at main manifold, 3no. at appliances --> 6 TOTAL

It feels unlikely that I would need to isolate one appliance whilst keeping the rest of the room operational.

On a statistical basis: You are almost 3 times as likely to have an issue with a long inaccessible pipe crossing the house than if you just have the 1 such pipe. Chances very low still though.

[TerryE]

3 hours ago, MortarThePoint said:

I'll have to remind myself which I decided against individual pipes per appliance. On thing I don't like about it is the shear number of pipes I have to pass through a cavity wall which currently doesn't have holes in it for the pipes.

I saw you post on this on another topic, and you concern about having to core lots of access holes.  I am not sure what your problem was here.  If this had been me, and I needed to run a lot of pipe runs through a block wall, then by far the simplest approach would have been to drill a set of vertical holes and bolster out half a block, then smooth out any rough edges with cement.  Feed the runs through and use some short lengths (150mm or whatever fits) crossways in the hole to act as spacers in the hold  to keep pipe separation.  Pack with mineral wool when all done to create the fire break.  Job done.

 

Saving a couple of runs to the manifold at the cost of all then extra jointwork local to each room makes absolutely no sense to me, as it involves extra effort and cost.

 

3 hours ago, MortarThePoint said:

On a statistical basis: You are almost 3 times as likely to have an issue with a long inaccessible pipe crossing the house than if you just have the 1 such pipe. Chances very low still though.

 

Sorry but this is flawed reasoning IMO.  The Hep2O type pipes have a practical life of maybe 50 years.  Earlier failures nearly alway occur in the fittings.  That's way the BRegs say that these should always be accessible.  By having each appliance / tap on its own unjointed pipe run with the only fittings at end appliance and at manifold, you don't have any hidden fitting within the building fabric. 

 

As to running buried pipework, the same rule applies as for electric cabling: only run directly horizontal or better vertical direct to the nearest floor / ceiling void; in the case of Pex pipework, mark run with aluminium tape so that it will be picked up by a cable/pipe detector.  Also given that most drill-through accidents occur when someone is adding wall fittings after the house is built, the critical number here is not the 3:1 that you mention, but how many buried tails you have and this basically the same for both approaches.  In my case  even if shit does happen, and I do drill a tail, then one twist at the manifold immediately isolates that one run, so I have one tap or whatever out of commission until the repair is done, rather than the whole room.  

 

PS.  I was just chatting about this with Jan, and her comment was "I can see where he is coming from; if we'd had a conventional build without decent floor voids and service cavities, then I have been tempted to do likewise so long as the room manifold were all easily accessible".  So maybe I am being a bit too evangelical about 1-1 plumbing. 🙃

Edited January 26, 2023 by TerryE

[Nickfromwales]

To go 90% of the way installing manifolds + radial pipes, and then discount 2 pipes and add extra satellite manifolds seems crazy to me tbh, and I’ll argue is more costly, more complex / impactful, and less efficient use of time / funds.
 

You have to purchase, mount ( and have access to ) the satellite manifold(s) and each manifold then has to have pipes from that to the individual outlets anyways!

Drilling 2 or 4 or 6 more holes through a breeze block would take about 30 mins ( and that’s if you had a cup of tea in the other hand which you didn’t want to spill ). But I would be doing what @TerryE says and knock out a letterbox sized hole, load it with short lengths of pvc pipe, and pull the Hep2o through those ( so they don’t get scratched badly by rough surfaces whilst being pulled for the long distances.  

 

The major benefits of radial are

a) zero joints between appliance and plant, and

b) uniform flow rates.

 

If you take 1x cold line to a satellite manifold then that would have to be 22mm pipe and a 3/4” manifold to achieve the same results / dynamic flow rates. More difficult / costly etc than 2 more 15mm or 10mm pipe runs. 👎

[Nickfromwales]

To not install a softener is madness, sorry. Knowing that all the crud and scale is growing on / in everything, from the day you switch on, and doing nothing proactively to defend against / prevent this from happening makes absolutely no sense to me whatsoever. 

Showering in glorious soft water is fantastic, vs the hotels I stay in ( when behind enemy lines ) where I need to use 3 times more shampoo / gel etc is something I couldn't cope with or get used to, let alone justify choosing NOT to mitigate against!

"Go soft or go home, lol".  

 

Probably a good time to remind the masses that manufacturers of certain equipment / appliances / outlets will stipulate that; beyond a certain PPM of hardness their warranty goes south and the installer / owner should mitigate, howsoever, to prevent damage / early failure of said equipment.

 

Just "no".

 

Sorry!

[MortarThePoint]

On 26/01/2023 at 14:11, Nickfromwales said:

Drilling 2 or 4 or 6 more holes through a breeze block would take about 30 mins

It's quite tough 10N aggregate block so harder work, but not the main concern.

 

I don't think flows would suffer as I don't expect the bath and shower in a room to be running at the same time. Satellite manifolds would only service one room.

 

All pipes passing through will then need to bend down to go to the manifolds, so that will be a bit tricky. Added to that is the plant room ceiling is 150mm lower than the kitchen ceiling void where all the pipes come from. I need to box an area out for all this above kitchen cabinets and have even wondered if I should put the main manifolds there.

 

All that said, I appreciate your experience and an trying to see if I can do 1-1.

[MortarThePoint]

Servicing loos and basin colds with 10mm would halve the number of core holes I drill for cold if using 38mm core drill. Such a hole allows 32mm pipe as conduit and 2x 15mm and 2x 10mm within (or 6x if only 10mm pipes). Otherwise I need 11x 38mm core holes for all pipes.

 

I've wondered about 78mm core with downpipe conduit.

 

Unfortunately, a letter box isn't practical. Would be better.

[MortarThePoint]

Below is a comparison between satellite manifolds and a 1:1 radial arrangement. Greyed out doesn't have to pass through the wall. In the 1:1 Radial arrangement, 29 pipes (17no. cold 15mm, 2no. cold 10mm, 6no. hot 15mm, and 4no. hot 10mm) have to pass awkwardly through the Kitchen/Utility wall. In the Satellite Manifold arrangement that comes down to 11 (5no. cold 15mm, 4no. hot 15mm, and 2no. hot 10mm). The Satellite Manifolds would have to be accessible, but wouldn't necessarily feature shutoffs.

 

1:1 Radials:

 

Satellite Manifolds:

 

 

 

[MortarThePoint]

@Nickfromwales and @TerryE This is the awkwardness of the pipe routing through the Kitchen/Utility wall. The diagram is to scale. I don't think I could core drill at an angle which would otherwise help greatly.

It already looks like I'll need to box in above the kitchen cabinets for this reason.

 

 

Edited January 29, 2023 by MortarThePoint

[TerryE]

@MortarThePoint, I am a bit confused here about your routing strategy.  It looks like you are routing your pipework horizontally within the walls around the living space.   What are you using for your ceiling joists?  We essentially did all of our horizontal routing with the floor voids as part of 1st fix -- that is before any plasterboarding was done -- which mean than the runs could take a pretty direct route to above or below the fitting, and then drop down or rise up to the fitting within the 44mm service cavity.  This is all pretty straight forward if you are using ecoJoists or OSB I-Beam joists, though in the latter case you do need to plan out your cross joist routes and add reinforcing plates around the access holes.  (You can also do this with solid joists but you do need to ensure that the structural integrity isn't compromised.)

 

We ran our services in reverse order of stiffness: foul water first, then MVHR, then potable water, and lastly electrics.  Perhaps this was because our previous house was a 300 year-old stone-built with Victorian additions, and this was a true PITA for routing electricals and plumbing.  Therefore on our new passive-class build we made a point of addressing these routing requirements as part of the initial design and well before any work on site.  In retrospect we were lucky in that some planning hassles delayed the whole start of build by about a year, so Jan and I had a lot of time to research issues in depth and to plan in solutions.

 

You seem to be facing difficulties that we avoided before we even laid our slab.  Where are you in the build lifecycle?  I get the impression that you seem to be struggling with issues that could have been avoided.

 

An example of this is that your main bathroom is 16m away from the manifold and the kitchen and GF loo 8m away.   We positioned our services cupboard centrally (the main riser was in a duct in the slab) so the most runs were 4m or so.  The longest run was to my son's ensuite in the loft floor and that was about 8m. 

Edited January 29, 2023 by TerryE

[MortarThePoint]

16 minutes ago, TerryE said:

struggling with issues that could have been avoided.

That's fair, it could have been thought out better. I am going through first fix and catching up some of those now. I wasn't aware of the manifold approach at design time and presumed I'd just have two pipes coming through, plus heating & wires. I know a normal builder wouldn't be worry about this in the slightest and would have the whole house off two pipes with Tees and Elbows a plenty. But that's not how we all roll around here which is good.

 

16 minutes ago, TerryE said:

What are you using for your ceiling joists?

The kitchen ceiling on the right of the diagram has Hollow Core Flooring (HCF, precast concrete) which is easy enough to drill through vertically, but not practical to route into the surface. Some suppliers provide that at design stage, but not mine. I'll have a suspended plasterboard ceiling (on the Gyplyner system) giving a service void of around 55 - 75mm (HCF is designed slightly bowed and may vary a bit by room). The Utility, left of diagram, is single storey and so the plasterboard ceiling will be screwed to the roof trusses.

 

The layout of the house is such that the Master bathroom and Guest bathroom are immediately above that Kitchen/Utility wall. In other words, higher up that Kitchen/Utility wall turns into the exterior wall of those bathrooms. The cylinder is well placed close to all outlets except the Family bathroom which is at the other end of the house. The fly in the ointment is getting through the blockwork cavity wall.

 

Actually, only the Family bathroom is served via the full S-bend. To most other outlets the pipes will need to head straight up.

 

Part of this whole game is rolling with the compromises and trying to make them as risk free as practically possible. I only really have three four options at this stage:

1. Utility Manifolds : totalling around 30 ports and running that many pipes (plus heating and wires) through about 12 core holes. Occupying the top corner of the room (above or inside kitchen wall cupboards) with some of the pipes' s-bends.
2. Kitchen Manifolds : minimal pipes (2 core holes) through wall then 30 ports and and pipes. Manifold housed in the top corner of the room (above or inside kitchen wall cupboards).
3. Satellite Manifolds : Smaller Utility manifolds, fewer wall holes, local accessible manifolds. Still a small amount of space taken up above/inside kitchen wall cupboards.
4. Go through the wall higher up : It's occurred to me I could go through the walls to the Master and Guest bathrooms in the roof space. I would have to insulate around all the pipes and ensure they get warmth from below, but it's an option.

Having once upon a time walked into my in-lasws' house with a burst loft tank raining inside, I am keen to avoid any pipes going anywhere near unheated spaces. I was the one who discovered the flood. Strange walking inside from the rain outside and into the rain inside before turning the light on.

[MortarThePoint]

The S-bends can be eased but using the dimension in and out of the diagram to help a little.

[MortarThePoint]

Ignoring the Kitchen feeds, which may be able to be down low and so much more choice there, the 38mm core holes could be split as follows:

 

That's a total of 4 core holes vs the 1:1 needing 10 (exc. kitchen). The compromises are:

• Master Cold manifold feeding bath, basin and loo cistern. May make sense to just use accessible Tees. Items not individually isolatable.
• Guest Cold manifold feeding shower, basin and loo cistern. May make sense to just use accessible Tees. Items not individually isolatable.
• Family Cold manifold feeding shower, bath, basin, and loo cistern. Would be kept accessible but items not individually isolatable.
• Family Hot manifold feeding shower and bath. That's effectively a Tee. Would be kept accessible but items not individually isolatable.
• One of the holes has 3no. 15mm Hep2O pipes in. That is a squeeze and may require some different conduit (3no. 15mm circles fit in one 32.5mm circle and the solvent weld pipe I am using as conduit is 32mm ID).
• Attic is a future renovation opportunity to add a loo. There are two compromises here (a) it is 10mm hot and cold (b) it's hot is shared with three colds so not ideal but feels minor.

Those feel like minor compromises for the significant benefits of reduced core holes and pipe grief. The coarsest level of isolation is at the room level (Family H & C, Master C, Guest C).

 

In terms of in use, I think the only compromise is:

• It does have the Guest loo cistern feed from the same main 15mm pipe as the Guest shower (cold). Probably worth stepping the loo cistern down to 10mm to hopefully keep the shower as the preferred path, though I could adjust the cistern inflow if required. Basin is also fed off this, though that is less binary than the loo filling.

I don't expect the bath and shower in the same room to be run at the same time.

 

Edited January 29, 2023 by MortarThePoint
corrected image numbering