I have been reading many posts in this forum for a month and would like to have some advice on the proposed system: We have a 100+ years old house two story with a large bungalow (13 years old) addition, total 3,000sqf + basement. It is basically two houses attached to each other with two oil furnaces. ___________________________________
Heatloss report:
Winder design conditions:
Outside db: 0F
Inside and design db: 72F

Heating summary: 84,846 Btuh
Sensible cooling equipment Load sizing: 26794 Btuh

Method F280, exposure category: sheltered, constuction category: Average, Number of stories 2.0, Area: 5476 ft2, volume 43808ft3.
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All 4 quotes offered 6 tons units with 3600ft closed loop.
The quote that I might go for is:
- Tranquility 27 TTV072 (6 tons)+desuperheater
- 10 kw heat strips
- Buffer tank 50gal (and change my 40gal tank for a 50gal one)
- Climated master thermostat with humidification control
- directional drill to tie in loop from the field into the home (so not to go through the 100 years old fondations)
- Change of duct work to tie up both houses duct work.
I am now in the process of checking references.
Is a humidifier needed (600 Cdn option)? I do have an air purification and filtering system in the new part of the house (where we stay 70% of the time).
As per their calculations, the geothermal unit should create 96% of the heat during winter (they have a software that is suppose to calculate it using the last 30 winter weather data) with 4% (colder days) on heat strips.
Thank you for any advice.

You might post this also on www.geoexchange.org

Seems reasonable at first blush

Design seems ok, the humi question is subjective.
It doesn't cost considerably more to add down the road. What kind did they want to use?
j

The other two companies quoting said that there was no way Geothermal will take care of the heatloss even a 6 ton...

The humidifier they were quoting was a Trane power humidifier. They ended up telling me that I should run the system for a year and figure ou if I need it down the road.

You may want to bump the electric back up to 15KW depending on how cold that loop gets and your voltage at the unit. Assuming the heat calcs are right of course.

Joe,

Do you really think a six ton unit is a good fit for 85,000BtuH heat load and only 27,000BtuH cooling load? It seems to me a six ton unit falls far too short on the heat load and is over kill for the cooling load.

A Tranquility 27  is rated for 54,100BtuH heating and 71,600BtuH second stage cooling and will produce about 50,000BtuH in first stage.

I'm not trying to criticize....just learn your thought process on the design.

Bergy

I cannot afford two units. and the complexity of having a 100 years old house attached to a 13 years old addition makes heating the house a tad more complex, I should have asked for a heatloss on each house.
It is basically two houses with a door connecting both of them.

So, the choice is a 6 ton that will heat up to -10C then rely on heat strips of sweaters or propane... Best would be two 4 tons in each house but the price tag is out of my reach.
I would love to know if the heatloss to too great for geothermal or if it is a viable solution. I would hate spending all the money and having a system that cannot heat the house.

1. Is a winter design temperature for your area of 0°F correct?

2. I would use your existing 40-gal DHW tank for the buffer if it were in good shape.

3. How many feet per ton are they planning on drilling; what size pipe; parallel or series configuration; what kind of flow centre; what kind of freeze protection & down to what temp?

4. F280 is the right method (or should I say ‘Wright’ method) – however, beware - the calcs are only as good as the accuracy of the data entered.

5. I would use at least a 20kW staged heat strip!

6. Insist on an ‘As Built Book’, mechanical flow meter (GPM), EWT & LWT meters!


SR

1. Is a winter design temperature for your area of 0°F correct?
YES

2. I would use your existing 40-gal DHW tank for the buffer if it were in good shape.
Considering that it is 10 years old, probably best to fork out the extra 400US and get two new tanks (one is included in the quote, the second is extra)

3. How many feet per ton are they planning on drilling; what size pipe; parallel or series configuration; what kind of flow centre; what kind of freeze protection & down to what temp?
3600ft of 3/4 black polyethelene CSA-448 CGC approved ground loop, I asked for the configuration and the info on the flow center, 20% ethanol

5. I would use at least a 20kW staged heat strip!
I wil ask them about it

6. Insist on an ‘As Built Book’, mechanical flow meter (GPM), EWT & LWT meters!
I did ask them and I will see what their answer will be

I do appreciate all the help to make my decision on a geothermal system.

6 tons is about as big as a single unit gets, HO can't afford two.

The 20 kw heat strip may require expensive electric service upgrades

Really hard for a geo heat pump sized for Canadian heat load to avoid being way oversized for cooling. Eventually there will be truly variable speed compressors able to ramp way down for light loads, but the industry isn't there yet.

HO may want to look into fossil backup in the larger of the two buildings, or look really hard at insulation / infiltration upgrades to knock down the heat load.

Berg based on info provided by poster the system satisfies 96% of the heating load. That's okay for me. They must get a little colder than my area or it would be more like 99% of the load.
I don't worry as much about cooling/dehumidification as others around here, but if we were to look at bin analysis* I think we'd fid that the system runs amply to ensure dehumidification, if not poster can look into clima dry.
Design is not perfect but it is adequate and the job offers extra challanges.
Joe
*remember the good old days before 2 stage you wouldn't have feared use of a 4 ton where there was a 2.5 ton cooling load if that's what it took to heat the house. Bin reports show that larger equipment often runs 1/2 hour per hour or so which is plenty for dehumi. with a modern fan coil.

Joe, your calculation must be similar as the company told me that their calculation came back to 98% of the heating load with a 6 ton. They have installed a 6 ton in a similar house with a 87608 Btus heatloss, I have to call him and see how happy he is with his install.

Thank you for all your help, I will go ahead with the installation (next month as they are super busy) and report back on the result. In the mean time, I will look at changing the old windows in the old house basement.

Not so fast, I said that you provided the comment that system handled 96% of the load (in your opening contribution). I've done no calculations pertaining to your home, I've simply made observations based on data you offered.
That said, if the data is accurate, I support the design.
J