Radiant Heating Issues

VivaVegas

I am in the process of doing a total remodel of a 1000 sq. ft. stick built, brick-veneered bungalow that is sitting on a full basement.

Currently, FAO and electric W/H is in place but.... the plan is to junk these two items in favour of a direct-vented, tankless, natural gas-fired H/W heater to look after all potable hot water requirements, as well as underfloor radiant heating.

In addition, there is a plan to add a new, fully basemented (is that a word?) sunroom to the rear of the house and that area would also receive underfloor radiant, as would the basement area which would become a home office.

I intend to treat the existing main floor area (1000 sq. ft) as a single zone and place 1/2" PEX tubing in each and every joist cavity.

The basement area of the proposed addition would become a second zone and the main floor area of the proposed sunroom would become the third zone.

While I have reasonable experience in a great number of areas, radiant heat is not an area I have ventured into previously, so any sound advice on the above would be appreciated.

Some of the areas of concern for me are as follows:

- I have heard that radiant heating directly under a toilet or tub is not a good idea. Anyone heard anything on these two issues?

- Extruded aluminum radiator track for PEX are available but one can also simply staple PEX directly to the underside of the subfloor. Your thoughts on these two methods and/or any references that would cause me to lean one way or the other would be helpful.

- Various forms of reflector/insulation products are out there to be installed between the joists and below the PEX. Which is the best? What issues did you have with 2x2 joist blocking?

- The tankless HWH currently considered by me as the best choice is a Japanese unit from a company called Rinnai. Any feedback would be appreciated.

Tony_12

Radiat Heat

Viva....The first thing I would do is have an accurate heat loss calculation performed on the bungalow. This can be done by any good supply house that sells radiant heating equipment. The heat loss calc. will then help determine the best and most efficeint way to radiant heat the space. Also, floor coverings and floor/subfloor thickness will be needed to determine tube spacing, water temp,panel placement, etc. Your supplier should be able to give you a pretty accurate tubing layout based on all this info.

VivaVegas

Tony, thanks for the help.

Can you tell me exactly as to what information someone would need in order to do an accurate heat loss survey and a proper tube layout?

Other than -

- floor plan of residence showing room sizes and uses
- locations of closets, kitchen cabinets, major appliances, toilets, tubs, sinks
- location, size and types of windows, doors and any other exterior wall penetrations
- values of insulation in walls, ceilings and basement.
- location of residence so they can determine climatac data
Regards,

VV