First, thanks to everyone who contributes to this forum, I've learned a lot!

My situation:

130 year old house in southwester Ontario, Canada (just north of lake Erie).  The house is about 1000 sq ft in 2 floors and the interior has been gutted and reinsulated with vapour barrier on the inside.  The windows and doors have all been replaced in the last 10 years with what seems like pretty decently performing windows and doors.  We are currently in the process of replacing the attic insulation with 2" of spray foam and cellulose up to R50.  We're also adding basement header spray foam and wall insulation (I believe to R-20).  So overall the house will be old, but reasonably upgraded.

The second part is that we're planning an addition of about 900 sq ft (2 storeys) that we'll attach to the east side of the house.  The addition is probably going to be ICF, slab on grad with infloor radiant heat.  I believe the addition will be much tighter sealed and insulated than the old house.  Oil is our current only options so I am convinced geothermal is the way to go for this house.  We're in the country with sandy / silty soil and plenty of space.

We will need something that services the older part of the house and the 2nd storey with forced air and something that provides the radiant system in the addition.  I have a quote for a Waterfurnace Synergy 4 ton system with a "geotank" and all required plumbing upgrades and 3000' of 3/4" tubing.  It comes in at about $30k (Cdn).  This seemed quite high to me, so I shopped for more quotes.  I found another company that I like a lot and they deal with "Enertran" which is made here in Canada, I think Orangeville.  I have a couple questions though:

1. Has anyone worked with Enertran geo systems?  Anything good or bad about them?

2. The system the contractor is proposing is a water to water system to provide the whole house heating, then a separate air handler (made by another company I think) to get heating / cooling into the forced air section of the house.  A buffer tank would be used to store hot or cold water in the winter/summer respectively.  This would also be a 4 ton system with 2500' of 1 1/4" tubing.  The overall cost of this system is coming in under $25k and I doesn't sound like I'm missing out on anything compared to the waterfurnace system.  Does this sound like a reasonable way to go?  Does this system work (water to water with separate air handler)?

I know I have to do the requisite background checks on the contractors (make sure they do a proper load calc, check references, etc.) but I want to make sure I'm pursuing something reasonable here.  Sorry for the long post; hoping someone has some insight.

Chris

1. I have no experience with Enertran, But would not be suprised to find out they are made by a big manufacturer. What is their warranty like.


2. It sounds like water to water would be a good fit. Sending hot/chilled water to an airhandler is common practice and works well.One thing I would be looking for is an outdoor reset control. If your heat pump is making 120 degree F water when you only need 100 degree F . You will lose efficiency.

Thanks for the feedback. I was hoping to hear more from others on something like this versus a "combined" system like the Waterfurnace synergy or the combined system from geosmart (I think it's called "premium Q)?

Ok, so from what you're saying I should ask if I can have control over the leaving temp of the geo system. If my buffer tank set point is 100 F, then I'm guessing it's not going to work well to have the geothermal output at that temperature. So I would likely want to control both the geothermal output temp and the buffer tank temp at the same time?

Chris

You might have misinterpreted HOTH's post. If you have a heating system able to operate on water heated to just 100 F (It can be done) the result will be a very good candidate for geo since a geo can produce 100F water at fairly high efficiency.

This is exactly what we have in our house. Although 4 tons seems a little high for your square footage with spray foam. I have 3000 ft and run a 3 ton unit, with a bit under your design temp in Michigan. Definitely do outdoor reset. We didn't and I'm in the middle of repiping to add it. If you have significant thermal mass, without it, you'll have lots of flywheeling going on.

We have a First Co 12VMB air handler, and a hard time finding even that one, but I'm sure others are out there. Make sure you include a buffer tank in the design.

Yes, I understand how the buffer tank will help things. Ok, I think I also get the point that 100 F design temp for the radiant heating will mean we can do a geothermal system efficiently.

Can someone explain what is meant by "outdoor reset"?

Chris

Outdoor reset refers to an outdoor temperature sensor coupled to a control which varies buffer tank temperature setpoint according to heat load inferred from outdoor temperature. The idea is to heat the radiant water only as much as needed to meet the heat load, and heat load more or less linearly tracks outdoor air temp (overlooking effects of wind and clouds for this discussion)

Geo-based radiant systems' efficiency is substantially affected by load side leaving water temperature, so keeping that as low as possible while still meeting heat load is desirable, and outdoor reset allows the leaving water setpoint temperature to vary dynamically.