Gas vs HeatPump Heating

Forums › Home Workshop DIY › Gas vs HeatPump Heating

hewittj

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#106078 17-Jul-2012 20:30

Hi there

After much searching on-line I have just been reading some useful forum threads around the area of gas central heating vs Heat Pumps.

I'm in the process of deciding on a heating option for our open plan lounge dining room area with around 55sqm of floor space, it has high ceilings at 3m. Until a few days ago we were convinced a Heat Pump was the best option but then had an installer suggest gas as an option. We already have gas cooking and hot water.

The installation costs are almost identical for gas heater or heat pump so I have been trying to calculate the relative running costs to see which option comes out cheaper. Over a 15 year period I have the gas heater at about $1000 more to run.

I wondered what experiences other forum users had and especially if anybody has switched from gas to heat pump or vice versa because of cost savings or any other benefits.

Thanks for your advice and help

Justin

[Moderator edit (MF): moved to correct forum]

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Wannabe Geek

#657227 17-Jul-2012 20:33

Go with the heat pump. It can do a lot more than a gas heater. Like dehumidifying etc and is really efficient. I have one in my house and it takes about 10 minutes to warm the lounge up.

scuwp

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#657246 17-Jul-2012 21:05

Use to have gas central heating in last house. Worked wonderfully but boy was it expensive to run. Had large heat pump installed in current place and it is a lot easier on the pocket. With only 55 sqm to heat I doubt you will need anything too big, my money is on the heat pump.

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Technofreak

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#657253 17-Jul-2012 21:16

We are in a similar situation trying to decide on a heat pump or gas.

They both have their advantages. We have been told that since we already have gas installed that gas is probably the better option for heating.

The heat pump certainly gives the advantage of being able to provide cooling in the summer assuming that is needed. The cost efficiency of the heat pump depends on the ambient outside temperature, the cooler it is is outside the more energy it needs to use to extract sufficient heat to warm your house.

Some people (my wife in particular) find heat pumps draughty, some like the ambience of the flame and fire of the gas. A heat pump will require more on going maintenance than a gas fire. At the end of the day I think it comes down to personal preference and location with respect to the cost of gas V electricity.

Having said all that I to am interested to hear others opinions/choices and why they have used a heat pump or gas.

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Niel

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#657254 17-Jul-2012 21:19

Around 5kW heat pump will probably do the job just fine. Depending where you are, if in Rotorua you will not get a warranty due to the sulphur in the air. If far south then the heat pump might stop working when it gets well below freezing outside and then gas might be a better solution. Canada gets a little but colder than NZ (understatement) and there central heating using gas is very effective as a heat pump cannot work in such cold conditions.

But gas cost per kwh (equivalent) is roughly the same as electricity per kwh so with a heat pump using power to transfer heat rather than generating heat, the running cost will probably be about 1/3 of gas.

So probably best to go heat pump, and make sure it is an inverter (i.e. the compressor motor has speed control, not just on/off). Most are inverter these days, but you still get the old ones.

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Handle9

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#657269 17-Jul-2012 21:46

Niel: Around 5kW heat pump will probably do the job just fine. Depending where you are, if in Rotorua you will not get a warranty due to the sulphur in the air. If far south then the heat pump might stop working when it gets well below freezing outside and then gas might be a better solution. Canada gets a little but colder than NZ (understatement) and there central heating using gas is very effective as a heat pump cannot work in such cold conditions.

But gas cost per kwh (equivalent) is roughly the same as electricity per kwh so with a heat pump using power to transfer heat rather than generating heat, the running cost will probably be about 1/3 of gas.

So probably best to go heat pump, and make sure it is an inverter (i.e. the compressor motor has speed control, not just on/off). Most are inverter these days, but you still get the old ones.

You will still get a warranty in Rotorua, you just need to use an installer who coats the coils (i.e. not a sparky who did a 3 day course at tech and has no idea what he's doing). The main mechanical companies in Rotorua who do heat pumps don't have too many issues because they know what they're doing and do an install suitable for the conditions.

IMO gas is a good option for a central heating solution. If you are just wanting to heat one room then a heat pump will probably work out a bit cheaper for the installed solution. You'll also get cooling rather than just heating. The only downside of a heatpump is that it probably won't last more than 10 years. A gas heater may last a bit longer but for your typical homeowner you're gone by the time that comes up.

As Niel has said heatpumps don't generally work too well in really cold conditions. We've been dealing with a central north island site where the large commercial variable refrigerant frequency system is basically continuously on defrost and can't get the space above 4 degrees. In that situation gas is a much better option.

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Snowflake

#657277 17-Jul-2012 22:24

i pay 6 cents per kWh for gas, and around 25-28 cents per winter kWh for electricty. (i was already paying for the gas pipe (hot water & cooking) so its pointless trying to factor daily charges into a calculation to make gas sound more expensive). even with the extra efficiency of the heatpump i still reckon its cheaper to run my central gas unit - plus it heats the *whole* house in 10 minutes, not just one room.

as i've mentioned a few times also, i see having no cooling option on the gas central as a benefit... most people i know with heat pumps end up using the aircon function during summer and therefore doubling their annual electricty bills.. it doesnt get that hot here that you have to have aircon...

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vexxxboy

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#657289 17-Jul-2012 22:50

i Live in Rotorua and have a 7kw heater installed, the installer who fitted it took it apart and sulphur proofed every part before installing it and it gets cold enough in Rotorua to really test it , this year its been down to -9 and i spend about $50-$60 a month to run it. After using it for 2 winters i wouldnt have any other heating .

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nakedmolerat

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#657291 17-Jul-2012 22:58

Go for heat pump... It is way better than gas.

JKRNZ

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#657296 17-Jul-2012 23:08

I live in Wadestown, Welington in old villa, 3.9m ceiling. After 3 yrs of discussion and evaluation we chose a gas heater (single, not central heating) over a heat pump. We have gas cooktop and water heating. Reasons for gas heater:

1. Heat pump is drafty and can cause dry eyes.
2. Heat pump was twice as expensive as gas heater.
3. Heat pumps generally have a warranty period of 5 yrs and an average lifespan of around 7 yrs.

After 15 months use we know this was the best decision for us. Hope this helps.

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Snowflake

#657308 17-Jul-2012 23:30

nakedmolerat: Go for heat pump... It is way better than gas.

why? because you said so?

perhaps you could add the reasons why you think that...

in many scenarios a heatpump may well be better than gas. not always though.

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timmmay

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#657366 18-Jul-2012 07:54

Heat pumps might last ten years or so, so factor in the lifetime of each.

A by-product of combustion of gas is water, so make sure the way it's set up brings heat into your house not moisture.

If you go heat pump don't go oversized. I had a firm put 6-7kw heat pump in my high ceiling'd lounge, but on cold days it pretty much never turned off. We upgraded it to a 10-12kw heat pump, which spends a lot of time turned off, which is better for noise and efficiency. Heat pumps working hard are less efficient than ones that are oversized and just ticking along.

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Handle9

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#657376 18-Jul-2012 08:17

timmmay:

A by-product of combustion of gas is water, so make sure the way it's set up brings heat into your house not moisture.

Timmmay is correct. The worst solution you could go for is an unflued gas heater. As well as water being a by product so is CO2 which makes you feel sleepy and lethargic. The water/CO2 combination is what also makes LPG heaters the devil.

If you go gas make sure you for a flued heater.

timmmay

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#657379 18-Jul-2012 08:20

Does flued even help much? You're still burning gas in your house. Central heating where the heat is captured and CO2 and H2O vented sounds better.

If I was doing central heating I'd try to do it with a really big heat pump, probably in the 15-20kw range.

davidcole

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#657385 18-Jul-2012 08:35

Definitely go flued and fan assisted if going gas. We have a large - 1983 Manufactured Flued Gas heater in the lounge, can wam pretty much the whole house about about 30 mins if the doors are open. Is only just needing a new fan now.

While they're expensive to install they seem to last pretty well as they're not full of complex electronics.

If doing it again, because I'd never give up my gas infinity hot water (you'd have to pry it out of my cold dead hands) I'd go gas central heating.

With flued fan assisted and gas central heating you're NOT pumping water into the house.

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#657389 18-Jul-2012 08:46

I had a plumber say he didn't like infinity water heating, said it took too long to start up and start supplying water.

Heat pumps have a huge fan, my Nocria seems like it could heat a small stadium. Give it ten minutes and the whole house isn't quite up to temperature, but it's surprisingly warm. I think gas can put out more heat though, and seems to be more widely used for central heating.

I have two heat pumps but I wish I'd put in one big one to central heat the house.

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