Cooling to Complement Radiator Central Heating in New Build Design

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MikeAqua

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#303230 26-Jan-2023 10:12

Designing a new house and have focussed so far on the heating side, which will be radiators. The last two weeks have reminded me that we use active cooling sporadically from November to March. Lets say it's 40 days per year with current climate conditions. Maybe more in El Nino years.

So we'll need a cooling system too. I'll be using shading and air flow to an extent to minimise heating of the house. But ... we're in Marlborough. When the NW blows, we'll need an active cooling system.

I could chuck in some heat pumps. They won't need to be high end just to cool. Would it matter if they're only run sporadically?

There are ceiling fans.

What else is there?

Edit: I forgot to add there will be lots and lots of solar panels.

Mike

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#3027392 26-Jan-2023 10:29

Have you considered a system that both heats and cools? If you want cooling your best (only?) option is heat pumps. Seems a waste to have heat pumps only for cooling, and a second system for heating.

Ducted heat pumps (guide), high wall / floor console heat pumps, either single units or multi-split.

Kim587

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#3027400 26-Jan-2023 10:40

I was about to say something similar. Heatpumps are pretty much the only game in town for active cooling. And pretty much every heatpump model available in the NZ market can do both heating and cooling (I believe overseas some can only run the cooling cycle). So you'll be putting in a system that just heats, and another system that does heating and cooling. Plus if you are thinking of maybe 3 heat pumps, you won't be far off the cost of a ducted system which is basically central heating run by a heat pump, so can heat and cool the whole house. Doing that would be a much more efficient way to spend your money than separate radiator and heat pump systems. Obviously only you can decide if the radiators are going to add enough value to your lifestyle to be worth the extra cost. I'm in the process of building right now too so am very tuned into the mindset of making my budget go as far as possible!

timmmay

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#3027406 26-Jan-2023 10:48

As someone with a ducted system, I would want one in any house I live in. They're effective, cheap to run, and quiet. Not as quiet as radiators, but we rarely hear ours. I'd just make one or two minor changes to what we have, considering per room returns, and using an air touch bypass rather than spill zone.

MikeAqua

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#3027434 26-Jan-2023 11:42

Radiator central heating is a must have - we both want it. Having stayed in houses that have it, there just isn't a substitute for that gentle, quiet heat, bringing every object in the house to a constant background temperature. We both dislike heat-pumps for heating.

The radiators will be powered by air-to-water heat pumps. I've used those both commercially and domestically and found them to be really effective. I could technically use the heat pumps to run the radiators cold. However, I don't think that will work very well.

It is a bit wasteful having two systems, but it sounds like that will be the only way to go. It won't add a big percentage to the overall cost of the house and it's our forever house. I could use a radiator for base heat and heat-pumps for top up. For example, set the radiators to 16*C and use the heat pumps to top up to 21*C or something like that.

Mike

timmmay

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#3027441 26-Jan-2023 11:56

Have you ever had ducted central heating in a house you've owned / stayed in? It might be worth trying to experience that to reduce costs a bit. But if you want radiators, sure, it's your money.

This summer we're finding cooling of bedrooms super valuable, it's getting hotter ever year.

Jase2985

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#3027466 26-Jan-2023 12:52

how are you heating your radiators?

timmmay

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#3027469 26-Jan-2023 12:56

Jase2985:

how are you heating your radiators?

Like this

MikeAqua:

The radiators will be powered by air-to-water heat pumps. I've used those both commercially and domestically and found them to be really effective. I could technically use the heat pumps to run the radiators cold. However, I don't think that will work very well.

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Kim587

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#3027470 26-Jan-2023 13:02

I used to think the same way about heatpump heating compared to a good old fireplace. But over time I realised that was because my main experience with heatpumps were undersized units installed in poorly insulated homes with lots of drafts - a triumvirate of problems guaranteed to make the heatpump look bad. Then I lived in a brand new fully insulated home and the heatpumps barely had to sit above idle to maintain the temperature and it was a completely different experience, much more comfortable and even temperatures. That will be even more the case now that the building code insulation standards are much higher, I think you'll find that keeping the house cool in summer will be a much bigger challenge than keeping it warm - that has certainly been my experience with recent new-builds.

The only drawback with the high-wall heatpumps I had in my first home was the temperature difference in the bedrooms which didn't have one, but that should be solved in house #2 I'm building with the ducted system. If there's a showhome or you know someone near you that has a ducted system, it would be worth going to check out because I have a hunch it might create the same experience you are looking for. Even if it just confirms that you still prefer the radiators, I'd suggest doing that for the peace of mind that you are making the best investment.

Sounds like a very exciting project though, have fun and there are a few people on here that have built before if you want any other tips or suggestions 🙂

mdf

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#3027505 26-Jan-2023 13:29

The only other active cooling system I've seen is evaporative cooling. These are popular in Australia (esp where humidity is low). A quick google shows some are available here, though mostly free standing c.f. built in.

I don't know the detail of how these compare with heat pumps / split cycle AC. The person we were staying with in Australia maintained they were much cheaper to run, but this was both Australian energy market and climate so NZ mileage may vary!

I know most NZ houses are damp so the idea of actively introducing moisture really doesn't appeal, but maybe a new build in Marlborough stacks up differently?

PS. I totally agree with you about the quality of radiator heat!

shk292

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#3027519 26-Jan-2023 14:29

The problem with evaporative systems is that they rely on breaking the first law of thermodynamics in order to be able to actually cool any room they're in. And unlike most laws, that one can't be broken

Decal

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#3027557 26-Jan-2023 15:45

Have you looked at the cooling options from your water to air heatpump?

https://www.centralheating.co.nz/central-heating-design/radiant-cooling/

mattenz

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#3027563 26-Jan-2023 15:58

Decal:

Have you looked at the cooling options from your water to air heatpump?

https://www.centralheating.co.nz/central-heating-design/radiant-cooling/

Not one mention of the major concern with those types of systems, which is where the moisture condenses.

tweake

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#3027580 26-Jan-2023 17:19

MikeAqua:

Designing a new house and have focussed so far on the heating side, which will be radiators. The last two weeks have reminded me that we use active cooling sporadically from November to March. Lets say it's 40 days per year with current climate conditions. Maybe more in El Nino years.

So we'll need a cooling system too. I'll be using shading and air flow to an extent to minimise heating of the house. But ... we're in Marlborough. When the NW blows, we'll need an active cooling system.

I could chuck in some heat pumps. They won't need to be high end just to cool. Would it matter if they're only run sporadically?

There are ceiling fans.

What else is there?

Edit: I forgot to add there will be lots and lots of solar panels.

what are you doing for ventilation?

you can get dedicated aircon, it doesn't have to be heat pumps. there is some differences between the two.

i think you really need to put a plan of the house and what your looking for. all these bits and pieces should all work together and that needs to be planned well. eg if your going to put ventilation in and have ducting, why not use ducted air con and have the ventilation connect into that. then of course you need to have space for all that gear, space for ducts etc. if you go to a good ventilation there is a few other tricks like using it to replace the bath fan.

there is lots of options that interconnect to each other.

tweake

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#3027631 26-Jan-2023 17:53

mdf: The only other active cooling system I've seen is evaporative cooling. These are popular in Australia (esp where humidity is low). A quick google shows some are available here, though mostly free standing c.f. built in.

I don't know the detail of how these compare with heat pumps / split cycle AC. The person we were staying with in Australia maintained they were much cheaper to run, but this was both Australian energy market and climate so NZ mileage may vary!

I know most NZ houses are damp so the idea of actively introducing moisture really doesn't appeal, but maybe a new build in Marlborough stacks up differently?

PS. I totally agree with you about the quality of radiator heat!

i just saw some advertised for sale lol.

simple problem is evaporative coolers don't work well in nz. thats simply because we are to humid. they work well in dry places, like parts of aussie.

but i saw a tv commercial where people said cool air coming out of it. if you look closely its done in a shopping mall which is air conditioned, which will have low humidity. so it works better there than in your home.

tweake

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#3027632 26-Jan-2023 18:02

Kim587:

That will be even more the case now that the building code insulation standards are much higher, I think you'll find that keeping the house cool in summer will be a much bigger challenge than keeping it warm - that has certainly been my experience with recent new-builds.

a lot of that is because of how houses are designed. people like "indoor outdoor flow" and like the idea of passive heating by the sun even tho its impractical. so you end up with houses that have excessive windows which increases the cost and lowers the insulation level. result is they cook in summer and are cold in winter.

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