comparing bids / comparing contractors
We are planning on replacing our 30+ year old oil furnace with a geo system in a 30 year old, 1900 sq ft home that was well built and well insulated. (located near Winnipeg, MB) I have contacted most contractors in our area, and have received 3 quotes. (several contractors did not even respond) All have suggested a horizontal ground loop system, but they range from a 4-ton to a 6-ton unit. (however, the one quoting the 6-ton revisited their calulations and now are quoting a 5-ton).
One contractor provided me with their full heat-loss calculation documentation, another showed it to me when presenting their quote, the 3rd didn't show me any proof of having done one and is also approx 30% higher. Needless to say, I have already disqualified their quote.
My biggest question now is why are they quoting different sized equipment / loop. The one that quoted the 4-ton even suggests that very little auxilary heat will be required as at 4-ton it provided most of our heating requirements whereas contractor #2 says the 5-ton will only provide 78% of the btu's required. I am planning on bringing this up with contractor #1 to have them review their calculations and/or ask them for a copy of their heat-loss calculations to see where the differences lie.
Having read the excellent information on these boards, I understand the imporatance of having system sized correctly and want to be sure that we have the correct equipment for our situation. Part of me thinks I shold err on the side of caution and go with the 5-ton to ensure we aren't undersized.
Both contractors I am considering have offered up references but I have not yet contacted them. I always question the validity of references as I do not feel anyone will be giving me a reference that will give any negative feedback... I have both contractors rated on an even footing from my dealings with them so far... If anyone could provide me with direction on how to qualify them it would be of great help! If I contact their references, what are some questions I should be asking?
On another note, while both are quoting WaterFurnance or rebranded WaterFurnace equipment (GeoStar), one did give me an option of Bard which looked attractive based on price alone. The WF's do seem to have a few more bells & whistles but it seems the Bard may be missing the coated coil that I have read has been a good technological advancement in heat pumps.
Another concern to me is both offer a 10 year warranty but the question of service comes in as I believe only one contractor in our area is a Bard dealer so if something happens to them I could have issues getting warranty honoured or any service at all.