Help Guide me, New HVAC in Old house
I am about to purchase an Old (1914) Brick and Stucco House in Minnesota. Before we move in, I will be Tearing out the Radiators and Boiler and installing a Forced Air System. This is a house we will fix up and likely live in for a few decades. New energy efficent windows will be istalled throughout. Main Floor is 1050 sq/ft upper level is 500sq ft and basement is 1050 unfinished but will be likely be finished 3 to 5 years down the road.
Any advice in system design and equipment/technology/efficency recomendations would be helpful. Although I am not wanting to spend a lot of money initially on equipment, (as it would cut into the budget of other areas of the renovation) I don't want to cut corners on the ductwork. Some day I would like to have a state of the art, efficent system and I don't want to hadcuff myself since I have the opportunity to be prepared.
Specifically, I am struggling to find any info on multi zone systems or ways to only heat and cool areas I am using.
Thanks in advance for any help!
Last edited by kjander; 07-16-2008 at 11:30 PM.
Find a contractor that offers zoning and get him to run a load calculation.
Zoning is awesome, if it is done properly. Search the BBB or look for good reputable local company.
Then you don't want the cheapest contractor.
The type of zoning you want. In order for it to work right. You need a contractor that doesn't just go by rules of thumb.
My big question... Why are you taking out the perfect type of heating system for our Minnesota Winters???
Hot water heat is by far the best comfort of heating in homes.
I would leave the hot water heat, and add mini-split system, or have a air handler in the attic for A/C.
Maybe he's going to put a York mod in.
....If he puts in one of the two Mods out there.... Then I may be OK with it.. Just a shame to yank out those nice old cast iron radaitor.
Originally Posted by beenthere
Originally Posted by kjander
A zoned forced air system is a real challenge for the typical residential contractor. As beenthere noted you need to be careful about who does the duct design and installation work. Even then zones can not be turned off.
The multi-split inverter driven variable capacity heat pump systems of Daikin, Sanyo and Mitsurbishi can do what you want done. Search each of these manufacturers for their own version of VRV/VRF (Variable Refrigerant Volume/Flow). These are highly efficient systems that can have up to nine indoor air handler units (each making up a zone with its own operating parameters including be completely turned off) connected to one outdoor unit. The outdoor unit can operate in a range of 29% to 113% on its nominal rating (3 - 5 tons) while each indoor air handler can operate from 10% to 100% of its nominal rating. Air handlers can be sized from capacities as small as 7K BTU to 48K BTU.
While I doubt you could fully heat your home, these systems put out substantially more heat than the typical US type heat pump. A 4 ton Daikin, depending on the indoor unit sizing, can have heat output of 48K BTU at 10*F. Using mayguy's suggestion of keeping a hot water system as your supplemental heat source makes a lot of sense. The highly efficient heat pump provides your primary heat with the hot water system supplementing that when the heat pump can not do it alone. Each manufacturer provides control interfaces for such a setup.
Each zone will only have refrigerant lines and a communication cable run to the air handler, then the ducting is for that unit, and a small zone sensor mounted a wall. This will eliminate the need to find space for elaborate ducting to go from one level to another. A central controller tucked away in a utility closest controls it all (can even control multiple outdoor units each connected to multiple indoor units) The physical size of the air handlers is quite small and can be more easily installed in a attic space. The more zones you create the more efficient the overall system operates.
Keep your current system and use the money for energy upgrades to the building shell. This will reduce your current load and save money on a smaller HVAC system. No reason to have a state of the art HVAC system in a leaky poorly insulated house. Windows have the lowest return on investment of energy upgrades although new windows are nice. Air sealing and insulation are the best ROI.
I agree, do yourself a favor, and keep the radiators and replace the boiler with a high efficiency mod/con unit (assuming this is hot water and not steam). In my opinion, you cannot beat the comfort of a properly working hydronic system. Not even with a york mod.
Originally Posted by mbarson
does the thumbs down mean he didn't like your suggestions? Wow
What do you guys think about going with a multi zone set up for the duct work and getting a cheaper, lower quality furnace to hold us over for a few years while we save for a geothermal heat pump and put that in ( as I undestand this replaces the need for a AC condensor?)
Is it accurate that the difference between a 92 and 95% furnace is all but irrelivant if you have a geothermal heat pump?