heat pump question

allenh

I was in Canada for a funeral last week. How cold was it? Minus 18 F and with wind chill -40 F. & C.

Electricity up there has to be real cheap as everyone had electric heat and heat pumps.

In one discussion they were telling me that even when its below freezing and the aux heaters are running it was still cheaper than say gas or electric. Does that make sense? Isn't using electric heaters on heat pump the same thing as electric heat???

Oh yes - can a geothermal system be used for hot water or is it strictly for forced air?

allenh

heat pump question...

I was in Canada for a funeral last week. How cold was it? Minus 18 F and with wind chill -40 F. & C.

Electricity up there has to be real cheap as everyone had electric heat or heat pumps.

In one discussion they were telling me that even when its below freezing and the aux heaters are running it was still cheaper than say gas or oil. Does that make sense? Isn't using electric heaters on heat pump the same thing as electric heat???

Can a geothermal system be used for hot water or is it strictly for forced air?

I saw a garage that made me very jealous. It was 28 ft * 28 ft. It had an electric heat boiler running water into radiant loops within the slab. It must have been 60 in there while it was 10 outside. He told me his heat bill for last month for 3500 sq feet 2 level home was 300 dollars. That included domestic water, cooking, clothes drier for 5 people.

Still haven't thawed out!

TIA,

Allen

flange

heat pumps generally have a balanced point. that is there is a point where they are no longer capable of maintaining a space alone, and must use some form of supplemental heat. generally this is around twenty eight or thirty degrees. once you go below this outdoor ambient you need the backup, be it electric or fossil. you can heat with electric really well, but around here you break the bank. keep in mind that up north, they also have a habit of really insulating their homes well. so, less heat loss, and less cost for electric can make it feasible to run as you describe.

Big Ed

No Stack Loss..

Just about all the energy with electric heat goes into heating .With a heat pump you are just moving the energy. You are taking the heat from outside and putting it inside.The electric strip turns on under the extreme winter condition.

When we burn fuel we convert stored energy into heat .We have to vent the poison gases that the conversion produces and with it some of the energy.

Electric heating is very efficant .Depends on the cost in your area of electricity .May be cheaper even with the stack loss to burn fuel....

Henry Q.

Heat Pumps

Canada has a very progressive building code related to insulation and HRV. They also have access to geothermal heat pumps (as we do here) that are hydronic units, made to produce heating water temperatures of 80-130F supplied to the heating distribution system. This is ideal for a properly laid out Radiant heating system. Some of the manufacturers make systems that are usable as a chiller with a separate air handler for cooling in the summer. Many of the systems in North America are only used for one or the other, but there have been units which did heating, cooling and DHW which were originally developed in Sweden, but are no longer available in the North American market. Low bid strikes again!

Craig_6

Something else to consider

Our power company (Illinois Power)offers an "all electric" rate with is lower than the standard electric rate. To qualify, you must not use gas for any space heating (DHW and cooking is OK). They come out and inspect your home/business. So your gas bill goes way down, your electric usage goes up some but you get a cheaper rate.

BTW, around here ground source heat pumps are performing quite well.

-cf
Champaign, Illinois

Wayne_12

heat pumps have the abiliy to perform many functions

Heat pumps have the capacity to perform many different functions, heating, cooling, dehumidification, forced air heating/cooling combination forced air/hydronic.

The limitations are endless. If we look behond our comfort zone, We find heat pumps are capable of providing many of our comforts we have come to expect. Think of the ground as a constant source of heat or cooling energy.

Like all design/build installations there are many variables. Heat pumps provide many of them.

Watching this site has confirmed there are many talented technicians, installers and owners out there that can and would install geothermal systems that would perform flawlessly.

Heat pumps are available for the small residential application to the largest building requiring heat/cooling or dometic water heat.

There are companies out there that have the ability to utilize the municiple water supply as the source of heat transfer.

The market in this country has yet to fully realize the potential energy savings available with current technology equipment. Are we waiting for new technology before we accept the technology that is currnetly out there or do we do what is best at the current time and adapt the new technology as it comes along.

All of the equipment utilized in a heat pump has been around for a long time. The refrigeration industry developed the tools required and refined the components to perform flawlessly.


There is nothing new or unique about a heat pump. Gather information and start studing about heat pumps. See how you can benefit from selling heat pumps. Become trained in the proper installation/service of heat pumps and reap the benefits. This wall is up to the challenge.

Thanks, I could go on and on. WD

Ken D.

Heat Pumps

In very cold outdoor climates, an air to air heat pump can be used efficiently if you over size. The idea is to have a bigger outdoor coil, hence more surface area for heat transfer. I have seen several of these sustems written about in Maine and Canada. The problem is if it is also used as air conditioning, poor performance will result. If used for heating only which would be acceptable in northern climates operation will be satisfactory. Otherwise a water source or earth coupled system is best. Ken D.

allenh

still want to know more...

If there were a small house that needed say 100 k btus. What size compressor would one need for heating purposes. I am curious to know what it would cost per hour for electricity to run at 12 cents per kilo hour.

Am I correct in thinking that forced hot water loops would not be able to be used. And that only forced hot air would work?

Henry Q.

Allen:
Forced warm water and warm water/chilled water to air systems are availible and work very well in cold climates. I like the idea of using a water to water heat pump which is able to make water of 80-130F for heating and can be used to provide radiant floor heating as well. Climatemaster(Stillwater,OK) makes several modular geothermal heat pumps which are able to be applied modularly in 3 & 5 ton sizes. You MUST do an accurate load calculation (ACCA Manual J or to size the system. Don't forget, no combustion means no air required for burning fuel and the infiltration rate is much lower than with a fossil-fuel system.These systems are also capable of producing chilled water and some domestic hot water

Jim Hurd

I'm interested in this, could you point me to these reports on the web anywhere?

How hard would it be to hook up two heat pumps, one for heating and one for cooling? Each should last longer. It would still be far cheaper than Geothermal.

Is related to what Nyle has done with their CCHP (www.nyletherm.com)?

Jim

Barry_2

Just my 2 cents for Ken

Assuming that you are referring to a higher efficiency outdoor unit as opposed to simply oversizing, I agree with half of what you are saying. Indeed, a larger outdor coil will result in a greater evaporator surface area and yes, it will increase the efficiency of the heat pump system in the heating mode. In periods of very cold weather, though, the system will most likely be operating below the balance point and will require the use of second stage heat, which can be, and very often is, very expensive... Especially if the source of that supplementary heat is electricity.

However, you also mentioned that the larger outdoor coil will not allow the system to operate efficiently in the warmer summer months. As I mentioned before, if you are simply referring to an oversized COIL and not an oversized system, you are mistaken. An oversized condenser coil (outdoor coil while operating inthe cooling mode) will resultin a larger heat exchange surface area and will result in lower head pressures.

Standard efficiency condensers operate with condenser saturation temperatures in the range from 30 to 35 degrees higher than ambient. For an R-22 system operating on an 85 degree day, the condenser saturation temp will be in the range of 110 to 115 degrees, equating to a high side pressure of approximately 230 psig.

If the condenser is oversized and is a high efficiency model, the condenser saturation temperature can be in the
range of about 105 degrees, giving us a head pressure of about 210 psig.

This lower head pressure will result in a lower heat of work, higher mass flow rate and a higher coefficient of performance for that system. These will give us HIGHER cooling capacity in the warmer months.

Although the increased cooling performance is likely to save some $$, The use of air-to-air heat pumps in very cold climates will most likely result in higher than normal heating costs...

allenh

I am trying to do

a rough calculation as to what it would cost for gas heat / in relation to electricity for a heat pump. That is why I picked a 100,000 btu asking what size compresser would be needed for that.

Outside space is not a problem as its all sand just under surface, have good friend with several size dozers - so it more tempting.

Last month used 278 ccf of gas = 361 dollars. Eight rooms, pretty well insulated, 4 rms up and 4 down.

allenh

I am trying to do

a rough calculation as to what it would cost for gas heat / in relation to electricity for a heat pump. That is why I picked a 100,000 btu asking what size compresser would be needed for that.

Outside space is not a problem as its all sand just under surface, have good friend with several size dozers - so it more tempting.

Last month used 278 ccf of gas = 361 dollars. Eight rooms, pretty well insulated, 4 rms up and 4 down. We had coldest weather here in Boston area a couple of weeks ago. And some of the places we manage couldn't even maintain temp as the systems were undersized apparantly. So the boilers were going constantly.

Dale

Canda

Depending on where in Canada, like Manitoba hydo elect is VERY cheap especially on an off peak rate, the US northwest used to be that way. And as the other post says it pays to ask your elect supplier about off peak options. Where I am residential elect off peak is possible for the whole house or for just water heating. In other parts of my state the co ops offer off peak for space and hot water but not cooking or general use. What puts many people off off peak is the extra electrician cost to wire the control breakers and extra meter.

Henry Q.

Heat Pump

Allen:

I was speaking only about geothermal systems in the Greater Boston area. If you are a customer of Nstar(formerly Boston Edison) or National Grid(formerly New England Electric) there is an extensive body of information about ground coupled heating and cooling systems applied in the Eastern New England area. When the price of Crude Oil dropped to $8.50/barrel several years ago, most economic studies wrote off the cost/benefit as unable to meet the payback models of 5-7 years.

Now that energy prices are over $30/barrel and Natural Gas costs have have increased substantially, the economics of a geothermal system make sense again. As I mentioned in my previous comment, low bid is not the best methop of planning for the long term outlook in a volatile industry such as ours.

I have successfully applied geothermal systems for heating, cooling and energy recovery over the last 25 years. The initial cost of the energy source is what sets apart these systems. They are never lowest first cost, but as the cost of fuel increases, the cost of total operation increases at a rate substantially less than a conventional system. This difference, subject to a large number of variables, determines the payback of the extra first cost.

I would not personally recommend air source heat pumps in the Northeast US unless they have a fossil fuel heating component set to come on at or near the balance point determined by the manufacturer's specifications. Sizing of ANY heat pump system is critical, and I have seen failures of geothermal and air source systems which were intentionally oversized by the designer and/or installer. In the Boston area, any heat pump which is substantially oversized will, when operated for cooling not provide the correct level of dehumidification required for comfort. In many cases, component failures occur because of lack of dehumidification (coil freeze, etc.) Also, compressors function best when they run for long cycles and are not subjected to frequent on/off cycling. Please try to avoid the concept that bigger is better when it comes to heat pump sizing. The industry standard of ACCA Manual J and its computer application Wright J by Wrightsoft of Bedford, MA will keep you on the right track for sizing and application. Let me know if this answers your questions. Thanks.