The insulation around the heat pump gubbins is paltry, only 10mm, and the whole thing doesn’t look very airtight. Losses from the room to the heat pump casing and ducts matter if you’re sending the air outside, but not if it’s staying in the house.
6/12
But…
The manual warns that you should only have both ducts indoors if the room is 20m3 or more. My utility room is about 15m3. There’s no space heating in utility room to counteract the cooling and my calcs suggest it could well get unacceptably cold.
7/12
So here’s the plan:
Have a supply air duct from the kitchen (red line) to the hot water heat pump (HWHP) and have a grille or two in the wall between the utility and the kitchen (blue lines) to allow the cooled air back out and the two rooms to equalise in pressure.
8/12
The kitchen is open plan with the dining room, meaning the water heater will be drawing heat from a much larger volume. What’s more the air to air minisplit heat pump is in the dining room, so it can compensate for the cooling more or less directly.
9/12
If the return air grilles are hidden behind the fridge then the air can cool the condenser coils on the back of the fridge, improving the efficiency of the fridge. 😎
10/12
I’m going to keep the tools and ducts to enable me to duct it to the outside at a later date if this doesn’t work. What might persuade me to do that?
- if parts of the house get too cold
- if air speeds in the kitchen impact on comfort
- if the unit is too noisy
11/12
- if air becomes too dry in winter (depending on temps heat pump runs at it might dehumidify air).
Best part of this plan? I avoid spending hours this weekend coring through concrete walls and can spend some more time with my kids! 🤣
12/12
Oh yeah, two more potential benefits:
Heat pump water heater switches to immersion below -7°C. That’s not a big deal for me, it hardly ever gets that cold, but it does elsewhere in Scotland, so it’d be good to test a solution that could work reliably in e.g. Braemar or Aviemore.
I can put a closeable vent between the utility and the sitting room, allowing me to cool that space in the summer, but not in the winter.
Some lovely carpentry happening in the house the last few days - bannister, skirting and a lovely integrated door facing/backboard for a Beast maker finger board.
Spent most of the day up in the loft putting back flooring that I’d lifted to get the MVHR ducting in place. Awkward sawing 18mm ply in a cramped space. It’s not a great space, and counts zero towards TFA, but will actually be pretty useful for storage.
Loft flooring done. A little tidying up to do and this will be a good space for storing outdoor kit.
Doing some testing on the A2A minisplit heat pump. I failed to program it to run overnight 🤦♂️
Been running it most of the day to see how well heat distributes from a single source. Seems pretty good, all rooms similar temp now. Should be better still with MVHR running.
Consistently impressed with details of aesthetics on our house from our architect. Black, white and tan colours, and horizontal lines, tie in well with neighbouring houses.
The colours even match the cat! He’s thought of everything!
Current move in date is 1st April (appropriately!). Please could I order a very cold snap in April? I don’t want to have to wait till winter to fully test how the house will perform in cold weather! 🤣
We have hot water! Testing flow rates and wait times for hot water with our 10mm radial distribution (15mm to bath). Seems good so far.
Cold tap in kitchen. 10mm Cu from manifold. Decent flow rate.
Kitchen hot tap. Less than 10s wait, and this was first hot I ran, so included 22mm to manifold.
Bathroom hot tap. Also <10s wait.
Ensuite shower room basin hot tap. Even quicker, I think cos this isn’t a low flow tap (reused from house).
Taps to bath. These are 15mm so longer wait but faster flow rate (difference not noticeable though).
Arostor quite noisy with ducting not going outdoors. Not cooling room too much with door to kitchen open so I think plan to duct it to include kitchen will work. Think noise should be ok if run mainly at night - can’t hear from bedrooms. If it’s too noisy I’ll duct it outside.
Not much done on house today but also, mercifully, not much left for me to do before moving in. Insulating this tap on outside to reduce heat loss through copper pipe. More to avoid condensation risk than because it’s a massive deal energy wise. Already done similar on inside (second pic) which seemed to have worked in last cold snap.
Tested out the shower. 6l/min but looks great flow, wait time for hot ~4s!
External wind tightness to incoming electrics duct today.
Update on shower. Just ran it into a bucket for a minute. It’s more like 9l/min so I’m guessing the plumber hasn’t fitted the flow restrictors yet, or they aren’t working. Will quiz them when they’re back in.
I thought it looked surprisingly powerful for 6l/min!
Reassured by space with table back in. We lost 100mm on external walls for insulation and service cavity, but we also lost a radiator so probably gained a bit of space overall.
Beautiful freezing cold morning on Monday. Ice on outside of windows, 16/17° inside off of only 4h of minisplit heating.
Some more thoughts/tests on 10mm (15mm for bath) radial hot water distribution:
- plumber reckoned my mains pressure was ~2.7 bar (if pressure is too low this system won’t work)
- multiple taps: 1 open to 2 open no noticeable difference. Open a 3rd & 1 drops a bit. No biggie
- flow reducers for showers not added yet, on order
- not timed bath fill yet, will do when have a plug!
- plumber reckoned it was a bit more work, but not loads
Decorators finished upstairs so I spent yesterday evening tidying up ready for moving the beds in. Looking great!
Bureau we picked up for £30 from local second hand furniture shop. Should work well in this space.
Hoping to repurpose one of these old worktops (from kitchen pre-retrofit) as a built-in desk for home office. Will need a good sand and oil!
Light shades going on. No particular logic to order I’m doing stuff here, just the order it comes out of container!
First bit of loft storage in use. This lot took up loads of floor space, but not much height, in the container, taking up hardly any room in loft.
Distant photo is looking at half the loft. Excited about having a decent amount of dry, warm, ventilated storage space.
Old bed rebuilt. Time for bed (unfortunately not here, yet).
Reused (from my daughter’s room pre-retrofit) but not very old carpet went on the stairs today. Looking good as new, less noisy and a lot less work than tidying up the old stairs!
Daughter’s bed; broken slats reinforced with spare bits of ply then bed rebuilt. Gonna need some padding on the wall at the bottom of the slide! 🤣
@EsTresidder Headbutting a power outlet could get dull!
Es Tresidder
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