We has heat!
After some delays, we finally have heat! The cause of the delays: first, it took us about two weeks to come to the realization that the slab heater and a pair of poorly-placed split-system air conditioners just wasn’t up to the task. After figuring out that the rebates would most likely cover the installation of a gas furnace, I rang up the local heating mob recommended by our electrician, and the sales guy came out immediately.
It took him about a week to spec out the two options, electric (refrigerated reverse cycle) and gas, and a few more days on top of that for the admin folk to get their heads around the energy certificates that’d probably pay for all of the gas install and about a third of an electric one, so we opted for the gas… even though I hate the idea of burning fossil fuels, economically I can’t justify it right now, hopefully things change in the ten years when the warranty is up.
It then took an excruciatingly long time for the parts to get delivered to their warehouse, but they showed up last week, so he rang me to organize a date. Monday looked good - they had an opening, the weather looked like it would cooperate (because the roof cavity is so small, they would have to remove several sheets of colourbond to gain access to parts of the house). They turned up bang on time on Monday morning, but they were down a worker due to illness (they were actually down two, but roped in an apprentice to come help) so we were warned fairly early that it probably wouldn’t be done that day.
I was optimistic they might sneak it in when their electrician came out to decommission the slab heater and connect the new outlet and light (an outlet to drive the controller and fan, and the light is apparently a requirement for new installs so the maintenance folks can see without a flashlight), but alas the last few bits just took an excruciatingly long time and they reached clock off time without finishing it. Alas!
Unfortunately for Beanie, the stomping around in the roof and all the activity really ruined her ability to take her requisite naps, so her behaviour in the evening was quite bad.
Up early the next morning to a house colder than I expected… I would have thought the slab would have held some heat due to a large thermal mass, but I’m suspecting it’s probably because so much of it is unpowered, and that probably explains the horrific bills.
They showed up to finish the job out, and it was all ready for testing by about 1pm on Tuesday. A few adjustments (the zone controllers are different than the typical ones the installer uses, and he managed to have them hooked up backwards: on is closed, off is opened, easily fixed but he did have to go back into the roof cavity, naturally), and a carbon monoxide test later and we were away.
Unfortunately, the nice weather for the install means we haven’t had to put it through it’s paces yet, but last night and this morning the house is definitely the most comfortable it’s been.
The system itself? It’s a Braemar TQ320, with a couple of zone controllers and a Seeley “Magiqtouch” thermostat. From what I can tell it all seems to do the job, the touch controller is serviceable but not amazing. I asked, and it will not integrate with our evaporative cooler’s thermostat. It doesn’t integrate with Zigbee or Z-wave, though it does have a wireless (as in, wifi) kit available, I’m not sure I want that. From what I can tell the Android and iOS app just mirrors the fairly average touch interface onto your phone, so all you gain is the ability to not have to get up. Lame.
Complaints so far: I was hoping to be able to get the return air central to the house: our goal later on is to remove the wall between the kitchen and what the previous owners used as a dining space, to open the rest of the place up, and then I was hoping to put the return air duct in what remained of the wall, turning it into a 400m (roughly) column between that space and where Sabriena and Duncan’s PCs are. Unfortunately it really needed to be in a wall, and the only reasonable place (other than doing a ceiling return, which the installer agreed with the sales guy would be really suboptimal for performance) was to give up part of the master closet. I’m OK with that, it just wasn’t my first preference.
The other issue is I originally asked the sales person about zoning off different parts of the house, and we ended up doing a bedroom zone (for both bedrooms) and a separate zone for my office, as I tend to like my space a bit colder than Sabriena likes hers. I thought this would mean separate thermostats, but apparently the default (and what the quote assumed) is just to have an on/off zone for those spaces, so that’s what we’ve got. I think it’ll work, and we’ll have the option (at extra cost, naturally) to later install additional thermostats if we want, but we’ll see how it goes first.
Update 2021-08-21: I have a spreadsheet I’ve been using to check the gas bill since the house in Pioneer Ct (where we wanted to answer the question “how much extra does the gas cost if we leave the heater on low all night instead of lighting it again in the morning”). I had to update the MJ:m^3 ratio and the cost breakpoints, but it’s pretty accurate. I measure the gas daily around the same time, and the actual gas bill is based off the average use per day, split up into four usage buckets, but it’s close enough on a daily basis and if I take the start and end measurements of the bill it’s exactly correct.
Our supply charge is $0.91AUD/day. Averaging out from the last bill (only about 40 days, but good enough) it looks like the water heater cost us a futher $1.00/day or thereabouts. With the thermostat on 21C (not the actual indoor temperature, as it looks like the termostat is out by a degree or two to a real thermometer and it’s locked so I cannot adjust it), our average total usage is about $8.69.
So subtract our supply charge (which we’d pay anyway unless I replaced the gas hot water heater) and the average usage of the water heater (again, same), and I figure the heater costs about $6.78AUD/day in the depths of winter.
For comparison, that’s about what it cost in Pioneer Ct to run the single space heater, which really only warmed the centre of the house, made a lot of whistling noises, and was generally uncomfortable. Oh, and the waterheater over there was undersized for a family of three - we could not all take a shower in the same night, or the last person would be finishing up with cold water… Sabriena was taking showers in the mornings to ensure this didn’t happen.
Furthermore, not having what’s left of the slab heater and the mini split-systems running slashed our electricity usage by about $8/day (some of that muted because on sunny days the PV array was eating most of that cost, and instead we’re now selling power back in the middle of the day for a measly quarter of what we would buy it for). It’s also worth noting that that’s with the slab heater thermostat set to 15C (no idea on the accuracy of those)… when we first moved in the thermostat was set to 22C (keep in mind it only operated at night, and for a handful of hours in the middle of the day), we’re down nearly $12/day from that point!
On the whole: I’m rather unhappy to be burning fossil fuels for heat, I’d have much preferred a phase-change system for heating and cooling, that I could then offset with a novelty oversized PV system on the roof, but from an economic perspective I just couldn’t make it happen right now… between the gas system being cheaper and the rebates being larger, and our mortgage being brand new it didn’t make sense to spend a significant chunk of our emergency savings to avoid fossil fuels. The heating bill is still fairly high - I expect it will lower a lot when we replace the giant single-paned windows around the various common spaces with more energy efficient ones - but the major difference being we’re no longer freezing (term used loosely, this house is in no way as cold as the house in Indiana was).
So I’m pretty happy with how it worked out - it could have worked out better had I a spare $20k laying around, but I don’t.
Update 2021-10-13: We got the first gas bill (they come every two months), and the results were basically as predicted. Roughly $200AUD a month, which is around half the price of the worst case slab heater costs, under which we were still thoroughly cold.
I still can’t help shake the feeling that environmentally it was the wrong thing, but the economic factors made it the only reasonable choice.