advice needed for home

[frenchman]

I'm puchasing an older 2 story home in minneapolis {1926}. Right now it has an old boiler {1965} in the basement and no a.c. I'm looking for advice as how to upgrade the mechanicals. I'm considering putting a forced air unit in the attic where there is plenty of room. I figure this is the best way to approach it ,taking care of both my heating and cooling. There is an unfinished basement and a nice chase from the attic {stacked closets}. Are there any codes, cocerns I have to be aware of? I'm an electrican by trade but will be hiring this one out. All input is appreciated.

[dougvhvac]

A full system cut-in is a pretty serious project, especially in a house that could have lath & plaster interior. Does sound like a nice project. Don't most installs in your region locate the equipment in the basement? Seems like that might be a bit easier. You might take a look at Unico - with 3" duct's and high pressure delivery, it's a slick system, particularly for older homes.

[penetr8or]

If you are dead set on putting your system in the attic, then a hig velocity system would probably be best. If your basement is unfinished (without a ceiling), and you have some head room, you could just put in a conventional system with the main duct trunks hanging off the floor joists.

[frenchman]

The mechanicals are almost always in the basement around here. I was just thinking, if I put the hvac in the attic and put in a tankless water heater, I would gain some much needed room. Eventually we would like to finish the space, and with 7 foot ceilings in the basement, this high velocity system sounds pretty cool. How large would the trunk have to be? If I did put it in the attic, what about the fact that the unit will subject to seasonal temps{100 in the summer etc}? I`m guessing this type of system still requires a condensing unit to be set outside?

[DanW13]

I think your best bet would be to rethink your decision and put the equipment in the basement and keep it in a warmer climate than your attic if at all possible as the attics get hot and when it needs repair in the summer that becomes unbearable at times for the tech guys to work up there. You mention you have stacked closets in the home so installing duct work shouldn't be too hard to run from the basement to the 2nd floor along with a few air returns back from each floor IMO, and yes the OD condensor will need to be plaed outside which would help in cutting cost of the install. It is always best if you can keep the equipment within the heated part of the home but not the attic if it can be avoided. I to think you might want to look into a HP for your climate, I talked to someone who has one here in Wisconsin and he asbolutely loves his Infinity hybrid heat system he has and says he has saved a bit of $$$$ since he had it installed last heating season of course it was based off he old unit that was replaced but he said even then he still would have put it in. He also put in zoning along with the Infinity as I have the same furnace he does 58MVC 3 stage mod very nice and IMO worth the money if you can afford it. But as oyu may have read on other post it's not all about the equipment especially in older homes where they lack insulation, better windows & doors, leaky duct work and such so before you replace or upgrade you may want to look first at doing some of those upgrades prior to have new equipment sized for your older 2 story. I also can tell you this I have a old farm house well over 100yr old and since last heating season I have put up foam bd insulation on the exterior along with tyvek house wrap over the foam bd. with new vinly siding, sealed all the exterior of my double pane windows, added a wrap around porch on the south and west side of my home, insulated my duct work as well as sealed everything prior to and some after the install of my Infinity 3 stage mod furnace and I am now able to keep my upstairs and down stairs within 1* in temps with my AC and keep my RH right at or under most of the time 50% but usually hangs around 46% the majority of the time. The money I spent on the exterior along with the new furnace will pay me back in realitively short order. Now had I not done all the work on the house and still put in the new furnace I wouldn't be sitting here today bragging about my ability to keep my house cooler without running the AC or warmer without running the furnace because the house would be a bit leaky, LOL !!! So as you can see from doing a few things inside and out prior to new equipment is esstieanal and plays a big part in the over all picture. Good Luck !!!

[dougvhvac]

I`m guessing this type of system still requires a condensing unit to be set outside?

Condenser goes outside as typical. Trunk is sized per zones fed, info @ http://www.unicosystem.com (there are other brands as well).

Attic poses several potential issues that basement might avoid, main one being egress. If your home has abundant space there, it could be just as easy.

[frenchman]

The attic is about 6 feet in the center and has plank flooring. I`ve been in alot of them and this one is better than most. Everything would be very accessable. If the pitch was greater, I would actually finish the space. After looking at some systems online I`m leaning towards a system mounted in the attic. Are there any systems to stay away from? We are talking about 1600sq ft ,so I dont think I need anything increadibly elaborate. We are planning on staying in the house a long time so we will spend the money on efficiency. I`m doing the renevation on this place on an electricians salary with help from buddys in the trades, I`m sure alot of you guys/gals can relate.

[dougvhvac]

With an attic having generous room, you could probably go conventional, skip the whole 'hi pressure' system thing. The stacked closets could help with a descending trunkline to the subfloor, giving you a path to distribute air to first floor. You mentioned a boiler, is it oil fired or other fuel?

[frenchman]

Natural gas

[dougvhvac]

With nat gas available, a sweet setup would be a 90+ variable speed fau in the attic, run the intake air and flue to gable end (no roof penetration) and locate a tankless water heater in the same space. You could also sidewall vent the water heater. Running a gas line up from the basement, taking a condensate drain down the same path (one for fau, one for evap coil). You'd free up your entire basement for other uses. Might make sense to run the refer lines down that same path, then subfloor to whatever perimeter location the condenser goes in.

[frenchman]

Sounds good! The only bummer is that the house has a hip roof so I wont be able to avoid the roof penetrations. Does variable speed make that big a difference? Is this house a candidate for zone valves or is that more than I need?

[dougvhvac]

Any 2 story home always works better with zoning, but variable speed is amazing. I was not sold on it till I put it in my house, but I made one mistake. For the Master Bed zone I just used a 2 stage furnace, but for the main living area I put in full variable speed. It is so much better (the variable) there's no comparison. 90% of the time you can't even tell it's running. Temperature is uniform throughout, and no harsh 'full blast' cool or heat when all the space needed was a little boost. I'll never install anything else unless a customer begs me not too! Too bad about the hip, but a couple of penetrations shouldn't be a big deal.

[frenchman]

So flr 2 = zone A, and main floor = zone B ? Would you add the bsmt on zone B or have a third zone? Does zoning ad to the overall eff?