ECN Forum Forums General Topics of the Trade Non-US Electrical Systems & Trades Air Conditioning?

I was under the impression that Heat Pumps didn't really work that well in colder climates. When I worked in Building Maintenance the Heat Pump units didn't seem to be able to do much when it really got cold and thats why we had backup resistance heating elements in them too.

Have they improved that much in the last 20 yrs?

Bill

there have been a lot of heat pumps installed around here lately. They seen to work fine untill the outside temp drops to below 10-15 degrees F or -10 degrees C. Then the supplemental heat strips kick in or the furnace will turn on. The cost is not that much more than a regular condensing unit.

There are pretty strict rules on gas heaters here, most if not all vent into a chimney, so no condensation probs. Stand-alone gas heaters have become pretty rare, they're mostly replacements (but a lot of old ones are still around). The typical heating system for apartments and smaller single-family homes is the wall-mount gas boiler in the kitchen or bathroom that supplies the radiators as well as hot water to bath and kitchen. Larger (and older) single family homes often have larger gas or oil burners located somewhere in the basement (the gas and oil "kettles" as they're called look just like djk's pics). Wood and coal heating is still legal and used, but not widely. Residential air condition is pretty much unknown, and only quite expensive new office buildings have aircon. There's the odd window unit though, they usually get a dedicated 16A circuit or are plugged into the nearest receptacle. Central systems run off 3ph, I've _never_ seen a real heavy load supplied by 1ph here in Vienna (unlike Germany where ranges are sometimes fed with 25A 1ph and 4mm2).
Heat pumps are starting up, but are mostly limited to the eco nuts. I think they're always combined with backup heating, unless they go down deep enough to ensure constant ground temperature.

Like all motors of any size in Scandinavia, heat pumps use 3-ph. Domestic air-cons are an exception since these units are rare and always imported. (They are even rated in BTU or whatever strange unit is used in the US.)

On the efficiency of heat pumps: The one my parents bought is claimed to work down to -18°C / 0°F

[This message has been edited by C-H (edited 10-06-2003).]

I've seen both high ampage 1 phase and 3 phase air conditioners in commercial units here in Ireland. It seems to depend very much on wheather there is a 1 phase or 3 phase supply already installed in the building.

The vast majority of the smaller units are made by Japanese companies... Toshiba & Mitsubishi mostly with some Dalkin units too. (Cassette air conditioners)

The full scale ducted gear would tend to be less likely to come from outside the EU and would obviously be 3 phase.

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As for gas fired heating systems.
They're generally have what's known as a "balanced flue"

basically the boiler's combustion chamber has no direct contact with the air in the house. Air is sucked in from outside with a fan through a 4" duct. The hot exhaust gas flows out through a smaller duct inside the larger duct.

Air coming in is preheated by the air going out.

It is impossible for carbon monoxide, condensation, or other gasses to escape from the boiler into the room they can only go outside.

Older boilers often had openings for air intakes into the room so if a chimney was blocked or running slow carbon monoxide could have leaked into the room.

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the big floor standing boilers in the pictures have fans in the burners and are not normally located indoors.

The balanced flue is also the standard arrangement in the U.K. for modern gas/oil heating systems. With the prevelance of modern central-heating, the old stand-alone gas fires are becoming a rarity these days.

The gas geysers that once graced the walls of many kitchens and bathrooms to provide hot water are probably considered archaic by most people now. These things were often open to the room atmosphere, and relied upon proper ventilation to provide suplpy air and exhaust, although sometimes the latter was provided by a chimney-type flue over the appliance. Of course, if the flue got blocked for any reason, the gases would accumulate in the room.

It sounds as though Ireland tried ducted-air heating about the same time period as Britain. Some small apartment blocks from the early 1970s have a kind of central storage heater system with ducts, but piped hot water to radiators is by far the most common modern method.

Ducted warm air is popular in caravans (travel trailers) and motorhomes though.

Indeed. The Gulf Stream keeps our islands relatively temperate, and in a few sheltered areas (e.g. Falmouth in the southwest of England) we even have palm trees growing outside!

What makes up complain about the weather so much here is the rain, wind, and overcast miserable dull days that are so frequent. But most people here just can't imagine the low winter temperatures of central Europe or the American MidWest.

Open geysers used to be very common here, almost every kitchen had them. They've been illegal to install for at least 10 years, I definitely know they were still perfectly legal when my parents wanted to install one around 1988 (but the gas line in the kitchen wasn't...). I guess there are still quite a few of them around. I prefer them to the 5l electric storage heaters as they heat the water much quicker and are more efficient. Modern ones still lok the same but vent into a chimney. Many of them are installed in old houses with drafty windows, so you don't hear of many accidents. In France and Belgium they're still perfectly legal (and it is claimed that this is the reason why these countries have a significantly higher number of CO deaths than for example Germany).

Paul:

Plenty of Palm trees growing happily here on the south coast of Ireland too. Even a few towns with palm tree lined streets! Looks a little weird

Due to an almost complete lack of any type of frost here it's possible to grow a lot of exotic plants without any problem.

According to my atlas, there's a small band which runs around the Cork and Kerry coasts of Ireland, and the coasts of Cornwall and part of Devon in England where the average January temperature is 45 deg. (In the case of western Cornwall, the areas meet to cover the whole far-west of the county.)

The is certainly the mildest winter climate temperature-wise in the islands, though unfortunately it's not the driest! I certainly remember my years living in Cornwall as having very mild winters. It did snow one year though!

Bill,
Yes, I'd tend to agree with you there.
A lot of the larger ducted systems that I've been involved with installing, have needed extra 2-stage heating element banks to supplement the normal heat produced by the compressor.
These banks are nearly always 3 phase units to balance the load over the supply better.
But, like anything, a Ducted Air Con system is only as good as the air temperature sensors that control it and if these aren't installed properly, ie: in the right places, they may as well not be there.
Bjarney,
Over here, the use of 3 phase for domestic A/C is pretty rare, you'd have to be heating a pretty big area to use a Cassette unit in someones lounge.
Having said that, I have wired a unit called a Multi-Head unit made by Mitsubishi and it had 6 indoor units and 1 outdoor unit and all the indoor units communicate with each other and the outdoor unit, it was a wiring nightmare, it was like hooking up a telephone exchange at the outdoor unit!.