Slight Electrical help - What is my HVAC guy saying - AC/Heat pump and kilowatts

[chris-md]

Anyone here electrically incline? I need some clarification here.

We are bidding out replacement of our AC system, with the inclusion of a heat pump (house has baseboard heating we want to rely less on - heat pump will be primary heat source with baseboard heating picking up whatever slack thereafter).

The guy said something about how we only get 10KW from the heat pump based on the breaker, and that its up to us if we want to upgrade to 15KW. When I asked him to explain again, his explanation was circular and clarified nothing.

I feel like there is a valid point, but I just dont' understand here, so I turn to you good people. Why would I want to upgrade my breaker to 15KW. What do I get out of doing so, what would it mean for the use of the system? What would I be missing out on if I didn't upgrade?

Any help is greatly appreciated!

 

[Kentuckienne]

J is an electrical engineer, so if you want to PM me he can talk to you by phone if you like.

A heat pump doesn't draw anything like that much power. Most heat pumps have resistance strips in them, an electrical heat strip like what's in your baseboard heaters. The idea is the heat pump extracts heat from the air, but at a certain temp - usually below freezing but the heat pump manufacturer will tell you - it can't extract any more heat energy, and the heat strips kick in to generate more heat. To get the stated efficiency of a heat pump, you have to leave the switch-over temp at the manufacturer's recommended setting. The air that blows out will feel cool, and the air that blows out when the heat strips are running will feel warm, and the heat pump will run more when it's cold because there is less heat in the air.

What the guy is probably saying is that your electrical panel will only support a heat pump with resistance strips that draw that much power. Can't say without seeing your panel...you probably have 100 amp service coming into the panel, then there are assorted breakers inside at different amps. Electric dryer for example requires more power than lights. So he may be saying that you would have to add some higher capacity breakers if the panel can support them, or you may need to upgrade your panel.

If you want to keep the electric baseboard heaters, you don't need the resistor strips in the heat pump. If you want to use strips in the heat pump and remove the baseboard heaters, you may be able to use their old breakers. If you like, send a picture of your panel (all the breakers inside visible) and some info about the proposed heat pump and he can tell you exactly what's going on. I'm so lucky to have him! He installed our panel and wired the entire house, in addition to doing the plumbing, making the tiles for the bathrooms, and making the flooring out of trees cut down to clear the lot. Of course there's no time for vacation, but who can go on vacation with a parrot anyway?

 

[SailBoat]

Wow Ms.K, that was one great way to take a fairy complicated subject and really do one great job clarifying. IMHO, the HVAC guy should be calling you to provide him with talking points.

Clearly you have been hanging around J way to long!!!

My much smaller two cents here is more related to heat pump technology. Selecting the correct technology is very important. For those of us in North America, the further North one goes the less effect each technology becomes. At some point, the technology costs more to buy, install and operate than it products. So, it is very important that you look at each type and understand, which provides the best Cost /Benefit for your area.

Again Wow Ms K!!!

 

[texsize]

Wow Ms.K, that was one great way to take a fairy complicated subject and really do one great job clarifying. IMHO, the HVAC guy should be calling you to provide him with talking points.

Clearly you have been hanging around J way to long!!!

My much smaller two cents here is more related to heat pump technology. Selecting the correct technology is very important. For those of us in North America, the further North one goes the less effect each technology becomes. At some point, the technology costs more to buy, install and operate than it products. So, it is very important that you look at each type and understand, which provides the best Cost /Benefit for your area.

Again Wow Ms K!!!

I cant give you technical advise but...
My father lives in Oregon and went from baseboard heaters to a heat pump system.
I don't think much of it.
When it gets good and cold it does not put out much heat.
there is something to be said for a heater you can stand next to and warm your bum

 

[chris-md]

All, thank you.

Kentuckienne, I feel like we're missing a point here. Something simpler than that. He left me with the impression I would gain something by upgrading the breaker for the ac unit, either greater functionality or greater efficiency.

Texsize - we're still keeping the baseboard heating, but trying to rely less on it. It's costing us $600 every 4-6 weeks. Absolutely unsustainable for us. And we have our thermostats turned below 65. If we can cut our oil heating in half, will be totally worth it.

 

[Scoza]

You mentioned a breaker which is essentially a reusable fuse. They are usually rated according to current not work. What I think you have been told is that the system you have had installed is wired into a 10 amp circuit(this is a standard single phase domestic circuit) but you cannot use this system to its full capabilities because it requires a 15amp circuit. It is not a case of just replacing the 10 amp breaker with a 15 amp breaker because it is there to protect the circuit if to much current is drawn. You we need to have a 15 amp circuit installed. Right now the system may trip the breaker because it is drawing over 10amps. Is it possible he said amps not kilowatts because kilowatts makes no sense.


Sent from my iPad using Tapatalk

 

[SailBoat]

You mentioned a breaker which is essentially a reusable fuse. They are usually rated according to current not work. What I think you have been told is that the system you have had installed is wired into a 10 amp circuit(this is a standard single phase domestic circuit) but you cannot use this system to its full capabilities because it requires a 15amp circuit. It is not a case of just replacing the 10 amp breaker with a 15 amp breaker because it is there to protect the circuit if to much current is drawn. You we need to have a 15 amp circuit installed. Right now the system may trip the breaker because it is drawing over 10amps. Is it possible he said amps not kilowatts because kilowatts makes no sense.

Sent from my iPad using Tapatalk

If that is all true, the HVAC guy clearly does not understand basic electrical terms and uses.

As stated above, fuses (circuit breakers) are provided for specific equipment to protect that equipment! Not to control the output of that equipment.

It is understandable that an HVAC guy or a plumber would understand electrical in the same light! To increase electric 'flow' (from the view point of forced air or water) the larger the available 'flow' the greater the flow can be made. So, going from 10 amps to 15 amps would in that frame of mind work! Wrong, but!

Hey, I am thinking that the HVAC guy is really taking about increasing the size of the Heating Unit itself. I have seen 'kilowatts' used to define a units output! Stupid, but I have seen it! Its what can happen when Marketing people get involved!

If that is in fact what is being relayed, Yes, you would need to increase the available amperage!

Most new Heating /Cooling systems are /have moved to (USA Terms) 240 VAC blower motors and condenser motors to reduce energy draw. I would believe that Heat Pump systems are doing the same thing! All that being true, it is common to have an HVAC guy taking about increasing the size of the Primary Electrical Panel from 100 Amps to 200 Amp Panels for two reason: The need for more space in the panel for adding circuit breakers and to have the available Panel capacity.

If all is true, you will need to get an Electrician anyway. So call somebody you can trust, i.e. someone that will get the proper permits and have the work inspected by the local governmental group. That way not only will you get the proper work done, but it will be to current electrical code!!! Very important, since if you have an electrical fire and the Insurance Company determines that your upgrades where not done to Code, They Do Not Have To Pay You!!!

 

[chris-md]

Thanks again all!!

I've been going back and forth with him on email about this, and I ALMOST understand. Here's what he said :

About the electric your electric line to attic has 60amp breaker which supports a backup heater of 10kw each 30amp is 5kw. Normally 10kw heater is installed with 2-3 ton heat pumps you have a 4 Ton heat pump normally you see a 15 or 20kw with 4 ton heat pump.
So if you want to make it a 15kw you might want to upgrade the electric wire and breaker to a larger one.



So either he undersized the unit to accommodate existing electric OR we can't optimally use the system with the existinnf electric. Still not clear but it's getting there.

 

[Kentuckienne]

I still think he's talking about the resistor strips used for backup heating. I believe he's saying that for a 4 ton system they would usually install a 15 or 20 KW heat strip but your breaker will only support a 10 KW one. If you are going to keep using your existing baseboard heaters, you can maybe do with the smaller heat source in the pump. But the heat strips in the pump will be more efficient because the warm air will circulate and only use the strips when it's really cold. Economics might favor taking out the baseboard heaters and rewiring their breaker to support the attic for the new unit.

 

[SailBoat]

At the end of the day, call your Electrician.

Understand that in the upper eastern half of the USA and Ontario Canada, electrical costs are poised to increase by as much as 50% over the next six to eight years. The cost increase is due to the transition from coal to natural gas plants and the continued increase in 'renewal energy' systems that are coming on-line. The increase in electrical costs off-sets their much higher cost to generate the same amount of energy as either gas or coal. Electric heating is not going to get any cheaper!

Have you looked a ground based systems that uses a liquid to gather ground heat?

Immersion heaters are the most effective way to extract heat from electricity. Think hot water heater. I have seen units that use this system with a hot water heater piped to an elongated radiator located in air exchanger in a continuous loop configuration.

I keep coming back to ground water systems, due to their year around use! Cool in Summer and warmth in the Winter.

 

[chris-md]

SONGe boiled I think down. Upgrade for optimal use. Took a while to understand but we finally have our answer. Jeez Louise!