Backup electric generators

[andyg2]

We are seriously considering the installation of a geothermal heat pump for our heating, A/C and hot water. Our problem is that our emergency generator is not of a sufficient size to run the system if we lose electricity. Currently, we have oil hot air and water with electric A/C. Our generator does not run the A/C, but it does allow us to have heat and hot water.

We had thought of having propane backup for the heat pump and hot water, which could be run by our generator, but apparently the Water Furnace units that our contractor uses come with a built-in electric backup.

We are looking for a solution so that we can have heat and hot water powered by our generator if we have a geothermal heat pump and lose power. Any ideas? Thanks.

[WF_Inc]

andyg2,

WaterFurnace’s IntelliStart™ is single phase soft starter which reduces the normal start current (LRA) by 70%, which may make it possible to use a generator with your unit. This option is available for units with the Copeland UltraTech Scroll dual stage compressor. We would suggest contacting your WaterFurnace dealer to discuss this option.

WaterFurnace International, Inc.

[andyg2]

Thanks. I will email them your post.

[rjkobbeman]

I had an IntelliStart installed a few months ago. I can confirm that they work as advertised. The whole reason I had it installed was so I could start my 6 ton unit with my portable generator.

Have lost power twice since... and the generator starts up the geo no problem. Once started, the geo doesn't take much to run.

[andyg2]

That's good to know. I'm looking at a 4 (or 5) ton unit and have a 12kw generator. Thanks.

[capncraigagain]

I had an IntelliStart installed a few months ago. I can confirm that they work as advertised. The whole reason I had it installed was so I could start my 6 ton unit with my portable generator.

Have lost power twice since... and the generator starts up the geo no problem. Once started, the geo doesn't take much to run.


What capacity portable generator do you use?

[rjkobbeman]

What capacity portable generator do you use?

I recently built my new home... and moved in last November. While building, I knew I wanted a backup generator. At first, I was going to purchase and install a 45kw Generac/Guardian whole house generator. Then Home Depot has a big sale on Guardian's big 17.5kw portable generators. I bought two of them instead of a whole house genny. Combined, I get 35kw out of them.

There are pros and cons to this installation:

Pros:

Cost. Big time savings.
They are portable, so I can use them anytime and anywhere I want

Cons:

They are portable, so I have to roll them out of the garage and hook them up manually.
Fuel. During power outages, getting fuel can sometimes be a problem. (A little planning is required here.)
Wiring. This can be a biggy for some, but I am a bit-head so it was fun for me. I will explain in more detail later.
Storage. They take up quite a bit of room.
Mileage. Things things suck the gas under heavy loads. Of course, I think a whole house generator does too. more about the size... not whether it is portable or not.

As far as wiring is concerned, here is what I did:

I have 400 amp service in my house. This is two 200 amp panels. Because I am using two generators instead of one, and each generator does NOT have a "full power" receptacle, I had to wire four outdoor receptacles. In order to tap into the generators full capacity, I had to wire up both the 50 amp receptacle AND the 30 amp receptacle on EACH of the generators. To do this, I installed and wired four sub panels in my basement. Two sub panels for each generator. Two sub panels are wired into on 200 amp panel. The other two sub panels are wired into the other 200 amp panel. All circuits in the sub panels are backup/generator circuits.

My Waterfurnace geothermal unit has three electrical circuits: One circuit that goes to the circuit board below. This runs the compressor and pumps. The second circuit goes to the 10kw (actually 9600 watts) emergency/auxillary heat. This runs the aux heat AND the air handler AND basic system circuit power. The third circuit goes to the 5kw (actually 4800 watt) emergency/auxillary heat. In order to run my system, I have to have power on both (at a minimum) the main compressor circuit AND the 10kw/air-handler circuit. Both of these circuits are 60 amp circuits (actually, I think I have a 70 amp breaker on the compressor circuit), so you can see that one generator cannot run both. All of this was taken into consideration when choosing which circuits to run to which sub panel... which goes to which generator.

If anyone has more questions, please ask...

As you can see, it was a bit of work to do this. However, I saved about $8k going with portables instead of a big whole house. Plus I was doing it all from scratch during home construction... so it really was easy. My one basement wall does get a lot comments though -- you can imagine seeing two big 200 amp panels along with four sub panels!

After all of this though, I started looking at the demands of the geo startup and quickly realized I needed the IntelliStart. It works great. We lost power a couple of weeks ago and hooked my generators up for the first time to the house. The geo started no problem. I think the LRA on my unit is 150 amps. This number of course is without the IntelliStart.

Overkill? Sure, but that is not the first time somebody has said that about one of my projects. Nothing better than the feeling of a/c running in your house when the power is out though. Of couse, I have A LOT more circuits energized with my generators than just the a/c (geo).

Depending on the size of your geo will dictate how big of a generator you will need. I don't know much about other manufacturers of geo, but I do know a bit about wiring/electricity... so if you have questions, fire away.

[capncraigagain]

RJKOBERMAN: Have you ever thought of mounting your portable generators and converting them to run on natural or LP gas? the fuel cost is much lower, although you lose some power. Another benefit to NG is that we rarely lose NG service during storms.

Have a great day, anyhow.

[rjkobbeman]

RJKOBERMAN: Have you ever thought of mounting your portable generators and converting them to run on natural or LP gas? the fuel cost is much lower, although you lose some power. Another benefit to NG is that we rarely lose NG service during storms.

Have a great day, anyhow.

Not really. We don't lose power very often. This is one of the reasons why I felt OK about going portable. The minor inconvenience of rolling them out and the minor added expense to operate them is OK.

I did buy some extension cords so I don't have to roll them very far. Seems to work fine.

Althought I have enough generator to run a TON of stuff in the house, in reality, I am barely taxing these guys. Fuel consumption isn't as bad a I initially feared.