*
In the design stages of a 1500 sq ft house in Canada – stick frame on 3 level slab. Have chosen Radiant floors for heating. I have a couple dilemmas though
1 – Where to put PEX – Since main floor will be on slab, I will probably put tubing into slab, except for kitchen and bath which are being built over a 4 ft crawlspace – In those areas would it be wise to recess the framing and lay Gypcrete to bring floor flush with slab??
2 – Subfloor on 2nd storey – is it better to continue with the Gypcrete from the kitchen, or is it worth it to try to work with Warmboard, anyone had experience with warmboard? Trouble working on exposed pipe till flooring is in??
3 – Since we are going with radiant floors we end up with THREE HVAC systems in the house. RFH heat, Heat Exchanger with condensate pans attached to mini duct system for cooling, amd Air exchanger to meet code. Does anyone know if the air exchangers can be tied into the mini ducts, or of a way to run an air exchanger without running all kinds of ducts? We are trying to avoid blowing dust around, and the only reason the Air exchanger is being installed is to meet code.
Replies
*
We have a similar setup, only with a dehumidifier instead of your air exchanger. That shares air returns with the Unico system. But the "fresh air" has its own grill (not much of a duct, just 4' from the unit, so no big deal).
For #1 & #2, what are your intended floor coverings? Do I understand right that part of floor is slab on grade and part is crawlspace?
*Subfloors on main floor will be either ceramic tile and Laminate, or if yours works well this winter, Ceramic tiles and bamboo. Upstairs Floors will be low grade carpeting so as to minimise insulation.On the main floor, yes the floor is mostly slab on grade, however rooms with plumbing will have a crawlspace under them (Kitchen, bath, Utility) simply for acess to the plumbing and for a little extra storage space.Thanks for your input.
*>if yours works well this winterI'm suddenly feeling the pressure to be an accurate reporter. I need some standards against which to compare. Perhaps a detailed picture of the same section of floor before heat and in Feb. I'll do my best to give an accurate description. In reality I'm more concerned about humidity (it's been 50 or so for months, and will likely drop soon) than heat, be/c our RFH temps are relatively low.And that's something to plan for with your place. The floor coverings and the type of installation affect the target heat of the water flowing through the tubes. And the heat affects the reaction of the materials. Our target heat is in the low 100's. For some installations it can be 125 or so. Plan ahead so that your heater is sized for the materials and your materials are appropriate for the temps.
*If you are bringing in just enough outside air to meet the code (which code?), the Mechanical Code (Int'l Mech Code, 1996) which applies where I am, requires that 0.35 air changes/hour or 15 cfm per person whichever is greater. For 1500 sq ft with 8 ft ceilings, that works out to 70 cfm (w/4 people of less). You can bring that to the return side of your air handling system to meet the fresh air requirements, no air exchanger necessary. I am assuming that your air handling system is about a 2-1/2 - 3 ton or 1000 - 1200 cfm, cooling. If you want to ventilate your house for comfort and air quality, you would need an energy/heat recovery unit and need 1 volume change per hour. At that rate, OA approaches 25-30% of the system, not something that works well.I have a question or two, first you said "Heat Exchanger with condensate pans attached to mini duct system for cooling", I don't follow you here.Second do you really plan to have so much dust in your house that you ventilation system will "blow dust all around"?By the way, operable windows are enough to meet the intent of the code for a residential living space, as long as kitchen and bathrooms are exhausted, dryer vented, etc..
*I assumed by "HX with condensate pans" he was referring to a cooling system that he hopes to work into the HRV duct work. I debated about doing that with the unmetered, 38F city water I get, but didn't bother (air temps are never over 75F). I just open windows to combat the solar gain.Yes, you could put the HX in the HRV ductwork. I did the reverse. I put some heat-fin tubing in my HRV return duct and run the hot water off the same thermostat as the main room of the house. Because 1) at -20F outside temps, the HRV return is 45-50F which is a bit chilly and 2) to provide a little quicker response than my 4" slab under carpet or 3 layers of wood gives by itself. -David
*Actually Tim, we do get a fair bit of dust around here. There are a few shipping yards not far from here and a bust road 3 doors down. My goal is to build a comfortable environment with as little infiltration of unfiltered air as possible. Code in our town requires an air exchanger regardless of windows, heat systems etc. Every home built in the county needs to have an air exchanger in it. My hope is to find a way to hook one up to a mini duct system such as the Unico System (I use this only as an example - I havn't researched these systems yet as this posting shows).I believe the code issue is a local one. I only learned of it when talking with a contractor onsite about how miserably a unit performed in my last home. Apparently it was one of the first installed under the new rules, and a few unscrupulous folks were just attaching them to the furnaces without running the proper ducts.
*My point is that forced air systems do not create dust. Sounds like you need to find out some specific details about the applicable code. Don't spend money based on word of mouth, find out exactly what is required and allowed.If allowed, the best way to utilize an air exchanger (commonly refered to as an energy recovery unit or a heat recovery unit, there is a difference) is to use the ERU as a exhaust fan for one or more bathrooms. You have to exhaust these anyway. Pipe (duct) the pre-conditioned fresh air from the ERU to the return of you air handler. That way, the air brought in is mixed with the air inside and cooled (or heated) with the rest of it.Note: some codes allow one rate for continuous exhaust and one for rate intermittant exhaust.To install an ERU as cheap as possible (in combination with an air handler), take exhaust from the return and add fresh air back to the return downstream (closer to the unit intake). It works, it meets most codes and installation is cheap because of the limited duct work req'd.
*
In the design stages of a 1500 sq ft house in Canada - stick frame on 3 level slab. Have chosen Radiant floors for heating. I have a couple dilemmas though
1 - Where to put PEX - Since main floor will be on slab, I will probably put tubing into slab, except for kitchen and bath which are being built over a 4 ft crawlspace - In those areas would it be wise to recess the framing and lay Gypcrete to bring floor flush with slab??
2 - Subfloor on 2nd storey - is it better to continue with the Gypcrete from the kitchen, or is it worth it to try to work with Warmboard, anyone had experience with warmboard? Trouble working on exposed pipe till flooring is in??
3 - Since we are going with radiant floors we end up with THREE HVAC systems in the house. RFH heat, Heat Exchanger with condensate pans attached to mini duct system for cooling, amd Air exchanger to meet code. Does anyone know if the air exchangers can be tied into the mini ducts, or of a way to run an air exchanger without running all kinds of ducts? We are trying to avoid blowing dust around, and the only reason the Air exchanger is being installed is to meet code.