Thursday, July 23, 2015

Keeping warm - the central heating edition

We are a day away from firing up our very own central heating system. It's a very un-Kiwi way of heating a home, but one that we hope will be both comfortable and efficient. I'll come back to how it works for us once it's up and running, but I wanted to share why we've chosen a central heating system instead of say, a heat pump or a fire.

When we moved into our house, it had two heat pumps and two HRV systems - one of each on each level. Both heat pumps did a good job of heating the rooms they were in. Unfortunately, the downstairs one is in our bedroom, which we prefer on the cool side anyway - 16-18 degrees is about right for sleeping, I reckon, so not much heating needed. Upstairs it was in what would have been the dining/living room for the previous owners, but will be dining/kitchen for us. Useful, but it leaves our lounge, the other three bedrooms, two bathrooms and hallway out in the cold.

And as for the HRVs - well, they did remove moisture from the air, but as I've written before, I'm not sold on the benefits of those systems; I prefer to minimise the moisture that ends up in the air and use the high-tech apparatus known to those in the trade as "windows" for ventilation.

We knew we'd have to do something about heating those extra spaces but it wasn't the immediate plan... Until we got into hot water.

Because we're adding a bathroom downstairs we knew we'd need some extra water heating at some stage, and since we're in the midst of relocating the kitchen, which (who knew?) involves plumbing, it made sense to look at water heating now, so that we don't end up running a whole bunch of new pipes and then needing to move them in a year or so.

So we started investigating our options. As well as the water heating, we had three distinct problem zones for heating: our son's downstairs bedroom (which bears the brunt of the bitter southerly, straight off Cook Strait); the new lounge; and the two upstairs bedrooms. We went through a lot of different options, which all had complex costs and benefits associated. So we did what anyone would do; we made a spreadsheet.

All the coolest people run their life with spreadsheets

As you can see, all of the options we came up with were pretty costly. The cheapest option was about $7k, and that didn't serve the whole house very well. The top of the range isn't really shown here because we only looked at cheaper central heating options - I'm sure a radiator system would have taken us well over the $20k mark. 

Having read a bit about it before we got the quote, we had high hopes that the gas central heating system might come in at a reasonable price. It's a newish system (Rinnai iHeat) which works off the Rinnai Infinity water heater, which means the water heating cost is bundled into the total.

Disappointingly, at just shy of $14k it was well over our $10k budget. And then my husband had a stroke of genius: what if we were to run the ducting ourselves? We suggested it to the gasfitter and he agreed that might be a good option. We're grateful that he was pragmatic*, because when the quote came back it was nearly $3k cheaper, which made it make sense for us (not to mention that we do quite enjoy the DIY malarkey and find it more satisfying to be part of the process and understand how it all works).

It's more than we were planning to spend on heating in the short term, but it makes more sense to do it now than having to patch heat pump holes in our freshly painted walls in a year or two - and we should get over $1000 back by selling the heat pumps and HRVs. So net cost should be a smidge under $10,000. 

The moral is: it's expensive, but actually not that crazy if you have several areas in your home that need heating. And for goodness' sake if you're thinking of installing two heat pumps and two HRVs think about whether central heating might make more sense! We feel quite sad that the previous owner spent all that money for very localised comfort when he could have had the whole house toasty.

Have you ever thought about getting central heating? If you have it, how do you find the running costs?

* understandably many tradies don't want DIY wannabes like us doing half the job, lest we try to blame them for our own ineptitude

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