I would like a recommendation from the experts. I have a 10+ year old 3000 sq ft. New England house with a warm air furnace. Have seperate trunks for upstairs and downstairs, seperate oil fired HWH. Currently uses a 5 ton outdoor unit. Want to upgrade to hydro air using two air handlers and condensers, boiler with indirect HWH for domestic HW. My main question is should I pay the additional money for variable speed air handlers? I plan on using 12 seer single speed 3 ton (adding basement cooling) outdoor units due to the relativly short cooling season, but like the benefits of variable speed handlers (quiet, low speed and ramping speed heating). Two contrators are trying to talk me out of spending the money on variable speed units. The other question I have is do I need humidity control thermostats, or is there a significant benefit for those in New England?
Have you had a load calculation done? If not this would be the starting point.
What boiler are you planning on using? An oil fired hot water heater (ofwh) would be 80% efiecient and may be able to supply all your needs for a considerable savings of initial investment.
After the load calc you may find you need the 5 ton unit for the upstairs alone.
Variable speed motors are typically used to get extra effiency out of gas furnaces, seems a little overboard to me, a good system should be quiet anyway. You could have the system set up so the air handlers were 2 stage via blower speed in heat which would give quieter operation during much of the heat operation.
Plan on using either Burnham V8 or Weil Mclain Gold series boiler(depending on contractor I choose)with 50 gal indirect HW tank. One HW coil on each air handler.
Originally posted by hvac-tech-lane Have you had a load calculation done? If not this would be the starting point.
Burnham V8 rated from 82.1% to 86.3% what would 2.1to 6.3%of your annual heating bill be? what would be the pay back point in years, with your proposed new system you will need to run the boiler year round for domestic hot water.
Hydro heat systems are designed for use with hot water heaters and will need modification to use with a boiler system. The circulator pump will need to be removed and a zone valve utilized for proper configuration.
hvac-tech-lane, thanks for your input but I don't plan on using a HW heater as a solution to my needs. Boiler is my choice. Cost is always a consideration but the configuration that I posted in my first post is the system I'm going with. I would still like responses to my original question, thanks.
WIth an oil fired boiler, you can't modulate the burner, so why bother with the added expense of VS? I would get a multi-speed AH that would allow you to lower the fan speed durring the heat season. Get an outdoor reset control like a tekmar to run the boiler up to 180° for the indirect and vary the water temp from 140-180° on the AH's as the outdoor temp changes. A humidifier will work better on a slower fan speed so you distribute more moisture with longer fan runs.
A VS blower will let you set your cfm for heat, and cfm for cooling independant of each other, and with a humidistat it will help to control humidity in your house during the cooling season.
The ramp up will help to prevent a blast of cold air in heating, and outdoor reset will save on your fuel bill.
check out the Energy Saving Products website. high velocity heating and cooling with hot water coils. they also have the JH series low velocity fan coils to adapt to your exisiting duct system.
And another good question would be: Why settle for a 12SEER? Go 13 & you're ready for 2006! And, besides, there's absolutely nothing wrong with wanting a VS air handler; they're the wave of the future, & one day you will no longer be able to get multi-speed air handlers. Go for broke, dude! Do what makes ya happy & don't let any contractor tell you what you want.
I wouldn't do the VS air handler if it were my house. No need to complicate the elaborate system hydro-air brings already. VS A/H are too much money anyways. Have the contractors set up the fan speeds accordingly, as they come thru on medium for heat, and high speed for cooling. Some less expensive models are set on high speed for both. A/H controls are available that will run the heat on low speed, and the A/C on medium or high. You set the speeds to fit your installation. I run nearly all heat settings on low speed, makes for more comfort, less cycling, less noise.
Almost forgot to add........do the Weil McLain Gold boiler with the Carlin Elite burner. Best USA made oil boiler combination in my opinion. I do lots of service work and this combination is by far the cleanest running combination I see, day in, day out.
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