Diesel heated central heating

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RedMoose

21 posts

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#251592 2-Jul-2019 16:48

HI

Has anyone had any experience with Diesel heated central heating systems, and using them to heat unit title addresses. As we are looking at a place at the moment that has an old diesel heating system in with radiators, and we are looking at upgrading it, and metering off the two titles. At the same time we are looking at getting the boiler to heat the hot water, as the current hot water systems needs to be replaced.

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#2268724 2-Jul-2019 18:52

Have you calculated the running costs? Last time I checked, LPG is far cheaper than diesel. And assuming that this is a commercial property, sometimes they have large capacity electricity connections, which have cheap per unit costs (although with expensive daily fees). So even plug in electric heaters may still be cheaper to run. And if you need aircon, then just get heatpumps for heating. If Natural gas is available, then that would likely be the cheapest for large scale heating and hot water.

To use the central heating system for hot water, you will need a cylinder with a heat exchange coil. They cost approx double that of a normal cylinder. And the standby costs to make hot water available all year round would be brutal. Unless you need very large amounts of hot water, a separate system is likely to be far better.

Im a plumber / gasfitter. Although my main experience with diesel heating was a job that was converting from diesel heating and hot water to Natural gas hot water. As that customer was spending lots of money on diesel.

Diesel heating only makes sense for large scale heating in the middle of nowhere.

And that is before you even start to consider environmental reasons.

Or are you looking at this on the basis of the cheapest setup costs? And not caring about the running costs as the tenants will have to pay the running costs.

RedMoose

21 posts

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#2268745 2-Jul-2019 19:45

Hi

@Aredwood, thank you for your reply, we are talking about a house that is in the middle of nowhere in the central north island. And based on research we have done from what we have seen Diesel and LPG Diesel appears to be at least 3 cents per Kilowatt cheaper than LPG, natural gas is not available, and neither is a large power connection. However, if there is some evidence to the contrary then we will happily look at alternatives.

We have considered heat pumps, however because of the layout of the house, we would be look at needing at least 4 heat pumps (that were suitable for a cold climate).

As alternative heat sources there is a log burning in the lounge of the main residence, heat panels will be installed in all bedrooms and hallways, plus a ventilation systems will be installed in both dwellings (a heat transfer will be installed in the unit with the fireplace as well).

raytaylor

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#2268813 2-Jul-2019 20:18

Would a heat pump water heating system work which then feeds the radiators?

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davidcole

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#2268816 2-Jul-2019 20:21

I don't have a diesel running radiators, but Natural gas to a water heater. It's not a dual though, so can't do tap water heating. But as long as you get the gas line in there's no real need to go down to one of them unless you're trying to reduce installation costs (ie one dual unit might be cheaper that a water heater for the radiator plus an infinity unit)

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Scott3

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#2269304 3-Jul-2019 13:32

Diesel central heating systems are getting quite rate in NZ (other than in high end camper-vans).

With regards to running costs, diesel has 9.7kWh or energy per Liter.

If we pay $1.60/L for our diesel, and burn it in a 80% efficient boiler, this works out to $0.206/kWh. I pay $0.144/kWh hour for my electricity in Auckland, so it would be cheaper to just use electric resistance heaters.

Note that there are some compliance requirements for storing bulk diesel, that mean the set up will cost quite a bit.

If you are in an area with natural gas, look at using that. Avoid bottled LPG as it runs even more expensive than diesel.

Are you in the "TLC" lines company area? - this could be a good reason to aviod electric heat.

If not, how big is the power connection that is available? Is a ducted heatpump (ideally one for each unit) a feasible option?

could also consider a wood pallet boiler, although I have heard mixed feedback.

Obraik

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#2269353 3-Jul-2019 13:58

RedMoose:

Hi

@Aredwood, thank you for your reply, we are talking about a house that is in the middle of nowhere in the central north island. And based on research we have done from what we have seen Diesel and LPG Diesel appears to be at least 3 cents per Kilowatt cheaper than LPG, natural gas is not available, and neither is a large power connection. However, if there is some evidence to the contrary then we will happily look at alternatives.

We have considered heat pumps, however because of the layout of the house, we would be look at needing at least 4 heat pumps (that were suitable for a cold climate).

As alternative heat sources there is a log burning in the lounge of the main residence, heat panels will be installed in all bedrooms and hallways, plus a ventilation systems will be installed in both dwellings (a heat transfer will be installed in the unit with the fireplace as well).

When you say you'd need 4 heat pumps, are you talking about your typical on the wall heat pumps or were you talking about 4 central air heat pump units? The latter seems like it would be a bit overkill for a house.

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Fred99

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#2269375 3-Jul-2019 14:53

Scott3: I pay $0.144/kWh hour for my electricity in Auckland

Unless that's "night rate", then you've got the cheapest electricity in the OECD I guess.

My BIL had a house in Q'town with diesel heating (sub floor) and water heating.

First problem was he installed it when diesel cost $0.60/litre, then it doubled.

Second problem was that the boiler failed just out of warranty - about 5 years, and cost over $5k to have replaced, meanwhile no heating except for an open fireplace, and no hot water for several weeks.

Third problem was that it was a new build, slab on grade on two levels, with ground settlement the slabs moved - not enough to cause any structural problems, but enough to break piping in the floors.

As a final comment, environmentally it sucks big time - and unless you want to leave the heating running 24/7, takes forever to get the house or part of it to a comfortable temp in winter.

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Fred99

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#2269377 3-Jul-2019 15:03

raytaylor:

Would a heat pump water heating system work which then feeds the radiators?

No. COP reduces with temperature differential, the hotter you try to get the water relative to the outside temp, the less energy efficient the system, the harder the compressor pumps work - the faster they wear out. It's much more efficient to use a regular heat pump pumping hot air out at say 30 deg, than trying to heat water to the 70 deg or more needed for radiators.

Some Daikin floor mounted heat pumps have a "radiant" mode where the fan runs only at a very low speed - effectively silent - and pipes on the front of the unit heat it up to maybe 50 deg. Probably okay for a bedroom, the one I have is more or less useless on that setting in a larger area, and probably far less efficient compared to when it's running in normal mode.

Beccara

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#2269395 3-Jul-2019 15:43

In the marine and RV space Webasto is good. We have one on our liveabord boat, Cheap and easy to run. Ours is a 2.2kw unit and sips fuel 20L lasts us all winter, They have hydro systems that use a hotwater loop etc etc. Don't know how well they would translate to a house but remote and off grid you can have spares ready to go.

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JeremyNzl

359 posts

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#2269419 3-Jul-2019 16:51

I have a condensing boiler, supposed to be (up to) 95% efficient if the marketing material is to be believed,

I have seen models that had hot water on demand with what I assume was a water tank and an appropriately sized heat exchanger on it for on-demand hot water.

17L per minute hot water http://grantengineering.ie/high-efficiency-heating_products/best-oil-boiler-brand/outdoor-combi-boilers/

If your running costs are business based diesel can be had for between 1.04 and 1.14 +gst last month looking at today's invoice.

jnimmo

1097 posts

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#2269451 3-Jul-2019 18:34

If you're looking at putting in a ventilation system anyway, could you put in a ducted heat pump instead?

I would've thought a heat pump would be an option for the radiators too but depends on the size of the radiator as you'd probably only be able to run it at 50 degrees or so - and would need a storage tank.

Scott3

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#2269545 3-Jul-2019 21:24

Fred99:

Scott3: I pay $0.144/kWh hour for my electricity in Auckland

Unless that's "night rate", then you've got the cheapest electricity in the OECD I guess.

My BIL had a house in Q'town with diesel heating (sub floor) and water heating.

First problem was he installed it when diesel cost $0.60/litre, then it doubled.

Second problem was that the boiler failed just out of warranty - about 5 years, and cost over $5k to have replaced, meanwhile no heating except for an open fireplace, and no hot water for several weeks.

Third problem was that it was a new build, slab on grade on two levels, with ground settlement the slabs moved - not enough to cause any structural problems, but enough to break piping in the floors.

As a final comment, environmentally it sucks big time - and unless you want to leave the heating running 24/7, takes forever to get the house or part of it to a comfortable temp in winter.

I made an error sorry. My (24hr) electricity rate is $0.1553, plus the AE levy of $0.0019. Combined it comes to $0.1572/kWh, or 15.72c/kWh. Unable to edit, but the point of my comment is unchanged.

Your comments regarding the rest of the OECD are wide of the mark. Power in Quebec runs at CAD 7.13c/kWh (NZD 8.134c/kWh) Source, We had an engineer come over from their for a project. Apparently they use resistance electric heater to heat their homes as power is so cheap.

Fred99

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#2269552 3-Jul-2019 21:44

Scott3:

I made an error sorry. My (24hr) electricity rate is $0.1553, plus the AE levy of $0.0019. Combined it comes to $0.1572/kWh, or 15.72c/kWh. No unable to edit, but the point of my comment is unchanged

I don't believe you. You seem to have made a mistake.

I suggest that if you make unbelievable claims, you need to show proof.

Please treat that as a challenge rather than an insult.

Scott3

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#2269553 3-Jul-2019 21:59

Fred99:

I don't believe you. You seem to have made a mistake.

I suggest that if you make unbelievable claims, you need to show proof.

Please treat that as a challenge rather than an insult.

Perhaps there is some confusion where i quoted prices in dollars rather than cents.

The below is for my residential address in Auckland. I am on a standard user plan with meridian. It wasn't an off the shelf plan. They contacted me after I didn't proceed with a quote I got from their website and offered me a better rate.

Low user plans have higher per kWh charges and Lower daily charges than my plan.

Extract from my latest bill:

For relevance to this thread, it would be great if OP could supply their main breaker size, power price per kWh, and if they are currently on a low user plan.

bfginger

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#2269613 4-Jul-2019 01:19

LPG and diesel could be subject to price rises over time.

Mitsubishi's hypercore enhanced heat pumps are rated to work at 100% down to -15.

http://mitsubishi-electric.co.nz/heatpump/c/8597/black-diamond-high-wall-heat-pumps

If not that a Daikin would probably be the best in that climate.

Fred99:

Third problem was that it was a new build, slab on grade on two levels, with ground settlement the slabs moved - not enough to cause any structural problems, but enough to break piping in the floors.

As a final comment, environmentally it sucks big time - and unless you want to leave the heating running 24/7, takes forever to get the house or part of it to a comfortable temp in winter.

That is why in Europe they like to install pipes above the concrete slab instead of inside of it

raytaylor:
Would a heat pump water heating system work which then feeds the radiators?

The Daikin Altherma can do that or feed a fancoil which can also cool. Lower temperature radiators may need to be upsized.

See https://www.youtube.com/watch?v=bs5uoQmFVgs

https://www.daikin.co.nz/sites/default/files/daikin-altherma-underfloor-heating-nz-brochure.pdf

I don't think the new R32 Altherma is available in New Zealand yet but that should be more efficient.

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