Comments/Advice on These Options?
Any comments on these configurations? The house is 8 years old and in Northern VA. There are two systems, this is for the main floor one. A second system is in the attic. In the winter peak heating bills can run up to $450 to $500 a month for one or two months. Summer AC bills run $200 to $300 for hot months.
I have added weatherstripping to all windows, spray foamed around the frames of a couple of the worst, and added extra insulation in floor joists at foundation.
Honeywell 2 stage thermostat
Coil: Matching, not specified
Comfort Sense 7000
None of the contractor did a Manual J calculation when I asked how they size the units. One said that the Manual J is filed with the county when the design of the house is built and it should be good.
Other comments were that my original system is mismatched with the furnace being too small for a 4 ton AC unit. They also change out the refrigerant lines and said that R410A is not compatible with R22 and if not flushed out properly it would cause problems.
One contractor told me to close off the outside air intake in the winter to save money. The house leaks provide enough air exchange. (The windows are drafty. The builder would not let me upgrade and with about 30 windows it would be small fortune with a long payback to replace them)
Only one contractor quoted a cold air return in the basement. There is not one now.
I think I need to call a couple more contractors. Many of these companies only have receptionists that answer phones and can’t talk about load calcs and leaves it to the sales rep.
In your (our) climate, you probably want to look at higher efficiency, 95% AFUE furnaces. I'm guessing PVC venting posed a problem? The $1500 tax credit available for the upgrade to 95% AFUE furnaces makes it worth it. All the systems you're comparing are good. The York furnace is modulating and would likely provide the best comfort in the winter with many stages of heating for longer runtimes and quieter operation. See about getting the Honeywell VisionPRO thermostat, TH8320U1008 or, better, the VisionPRO IAQ, YTH9421C1002.
You needa load calc. For more info on the importance of load calcs see the FAQ link below.
Load calcs maximize your fuel savings
8 years young and you’re replacing the equipment already?
Something is seriously wrong with the original instillation and or construction.
Replacing leaking windows and doors and adding insulation has a faster payback then replacing the equipment.
Insist a Manual “J” as well as Manual “D” is performed. (You get the reports when the contract is signed)
Having lived many years in a cold climate, I appreciate a well insulated house with good windows and doors. In this case it would cost upwards of 40 to 50K to replace the windows, with a long payback. I've done what I can with replacing and adding extra weatherstripping to them.
Originally Posted by pecmsg
The existing systems are not the greatest, the ACs have failed in the neighborhood at about 30 to 40%, some as quickly as 5 years. The decision is not if the AC will fail, but when and in high cooling season without manufacturer promotions, I would only replace the AC with a 14 SEER unit or so at best. If I can get a tax credit and system rebate, the combo should only be a reasonable amount more than the AC alone. That's why we are considering it.
Do the refrigerant lines need to be replaced and is there any benefit to adding a cold air return to the basement?
I take there is not much difference in these configurations? All contractors said a 95% furnace would be a long payback. Do any of these qualify for the tax credit. I think most contractors are still learning the details.
You’re asking about the equipment but should be looking at the entire system. Heater, A/C Heat-Pump, Supply and Return ducts.
A new heater / A/C on poorly designed ducts is worthless.
You need someone to look at the entire system, not the individual components.
That's why we are considering replacing the whole system now and not just the AC under duress when it fails in the heat of summer.
Originally Posted by pecmsg
I called contractors to look at the entire system:
One guy gave me Carrier performance options and Infinity. I was leaning towards a system replacement with Infinity to get variable speed. They suggested a return duct in the basement.
Another guy told me to close off the outside air intake in winter and that the furnace was undersized.
I was also told to change the lines.
None of them commented that the duct work needed changing. This system services the main floor and basement.
That’s why I’m asking here for opinions if I should change the lines, add a return or block the fresh air intake? Or if I should ask for something else.
All of them gave me options from mid level AC only to combos of furnace and AC. I got one heat pump quote as an option Carrier 25HNA648A003 which needs the Infinity furnace.
I gathered that for comfort, humidity control in summer, that a good option to consider was a 2 stage condenser with a variable speed furnace and a good controller.
Any other opinions?
Uncontrolled fresh air is your worse enemy.
Either shut it off. Or put a controller on it.
Looks like everybody is increasing your furnace size.
Might want to request a load calc be done, if you want to save money on your heating bill.
If you want a company who will take care of your concerns and do it right the first time call these guys:
Ask for Terry or Justin
PS I don't work there anymore but I wish I could, they're the only co. in our area that I would consider top notch
I am the Stig
Thanks, Would it worthwhile to install a motorized damper or even an HRV?
Originally Posted by beenthere
I was thinking of buying the HVAC calc software to check the calculations. Would it give a first time user good results?
If you take your time with HVAC CALC, it can be very beneficial to use it.
An HRV can help alot.
But at minimum a motorized damper should be installed, And then the damper set to only open as much as needed for the amount of fresh air your house needs.
I know what you are going through. I purchased my current home about three years ago and was shocked at the energy consumptions. My knee jerk reaction was to replace the heat and cooling systems with the most energy efficient stuff I could find. I had several contractors out who could not tell me what was wrong with what I had, but assured me that if I gave them many thousands of dollars their system would resolve the problem. I'm glad I didn't do it and took time to fully understand what the issues really were.
First off, the operating cost saving in our area (I'm a few counties to the west of DC) for the highest efficiency equipment PERFECTLY installed on perfect duct work compared to what you have will be less than you think - probably less than $400 per year. From you have said about your neighbors systems failing in such a short period suggests there are other problems such as poorly designed and installed duct work. Very, very common problem. New a/c and furnace installed on an existing poorly designed and installed duct work is a total waste of your hard earned money. I will bet that none of the bids you have did anything to test the duct work. Send them all walking.
My suggestion is to spend some time reading and this site is a good place to start. Read everything you can on air flow and the thermal efficiency of buildings. Then when you have a general understanding as to what the issues are hire contractors that are specific to what you need. The first might be one that is an expert (and not just any HVAC company as most don't have a clue) in air flow issues. They will be able to analyze the duct system to determine how much air it can move with reasonable resistance. They will be able to determine exactly how much air is being delivered to each room. They will help you understand how much air leakage you have with the system in the attic (it could easily be 30%+ of the air flow and that causes other problems). Then they can tell you what will need to be done to correct the problems. Often the existing duct work can be fixed without the cost of starting over.
Next consider having a blower door test done to determine the air leakage of the structure. If the house is leaky (sounds like the cheap builder grade windows are at least part of the problem) higher efficiency equipment isn't going to help.
You can make the equipment you have perform higher in efficiency by resolving the poor installation issues and keeping the air that you have paid to heat and cool in the home and the outside air out. It will save you more than new equipment. Plus, when you tighten up the building envelope you get dividends on that everyday without having to pay any more for it.