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Building a 3400 sq. ft home. One contractor wants to do a 3 zone heating using one furnace and another wants to use dual systems. Anyone have thoughts about which is best? Also looking at using a Bosh tankless gas water heater instead of a tank. Specs look impressive. My wife is always using up the hot water in her Jacuzzi. Anyone use it and have an opinion?
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Unless the house rambles over a few acres, I'd go with one furnace. There will be an economy of scale. Throw in a few thermostatically controlled dampers if there is a concern about one area needing a different faction of the total heat at different times. For instance, if afternoon solar input is going to over heat the west rooms while the eastern rooms need furnce heat.
There have been many discussions in the archives about tankless heater, their pros, and cons. It sounds like you're not pinching pennies, so I'd recommend the best of both: feed an electric hot water heater from the tankless. You'll be able to use two showers at the same time, have very even flow, and can run a single shower forever. Those things are not all true if you go either tanked OR tankless. No flue losses from an electric tank and you can wrap extra insulation around it. Set the electric HWH thermstat below the normal output of the tankless so it will almost never come on. -David
*I think you will find that if you do a load analysis on your hot water GPM's, that the tankless heaters will not be able to supply sufficient volume for domestic hot water purposes. In a low flow closed hydronic space heating system, tankless probably has the capacity but why not use the extra BTU's produced in a storage hot water heater used for domestic supply.
*I am building a 3800 q. foot home (on an island in the upper peninsula of Michigan) that only has electrical service. No gas, no LPG, no oil.Plans are for an hydronic heating system under the sub floor. Radiantec has estimated that I need a heater that will provide 225,000 BTU's, but they have no recommendations for an electric heater (only gas).Questions are:1) What electric heaters would you recommend to provide domestic hot water and supply hot water to the hydronic heating system?2) What manufacturers of hydronic heating systems do you recommend?3) What tubing do you recommend.
*DavidB: You've hijacked someone else's thread which is not so much an ettiquete thing as it won't get you as many answers as opening up your own thread. But here goes:That's a LOT of BTUs for a new house. And don't tell me about an extreme climate :-). If I was building a house in UP (and, climatically, I essentially did when I built my house up here), I would aim to create a very well insulated and tight house. If there is only electric to work with, it would very, very well insulated and tight. Like an inch or two of spray foam onto the sheathing and onto the vent-channel under the roofing. And then fill the rest of the bays with FG batting (cheap) or more spray foam ($$).Well-built, such a house at 3800 sq ft would take 40,000 BTU/hr (12 kilowatts of resistance heat) at -40F which seems like a sufficiently conservative design temperature. Plus domestic hot water needs. So you need to assembly that much heating capacity which could be a one electric on-demand water heater or two tanked electric HWHs. On-demands are great for long showers, but I'd go for the cheaper tanked HWHs. One for domestic. And one with its elements wired in parallel (to separate breakers so they can turn on at the same time) for the hydronic. I'd feed the domestic HWH from the hydronic HWH if your code allows because you won't notice a interuption of hydronic heat for 30 minutes, but you sure will notice the end of the hot water if you're in the shower.Are you sure there's no option for fuel oil? That seems very unlikely to me. The fuel oil company are used to servicing some of their customers out in the boonies. And that will a lot cheaper way to buy BTU's than to make the electric meter spin.And check why radiantec thinks you need so much heat. Maybe they are just being very conservative (they only get yelled at if there is not enought heat). Or maybe the specs you sent them were not for a really snug house.If you inist on electric only, check into heat pumps. If you have the acreage for a ground-loop or can drill a well for a groundwater heat sink, heat pumps can work nicely with radiant floors. You don't need a very high temperature for radiant floors (compared to forced air heating) which allows for efficient heat pump use. -David
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Building a 3400 sq. ft home. One contractor wants to do a 3 zone heating using one furnace and another wants to use dual systems. Anyone have thoughts about which is best? Also looking at using a Bosh tankless gas water heater instead of a tank. Specs look impressive. My wife is always using up the hot water in her Jacuzzi. Anyone use it and have an opinion?