Ductwork for hrv

[sheetmtlman]

Is it necessary to run ductwork up the stud space when installing grills for a hrv installation or can you just cut out the plate of the wall and hook on down below with a boot and pipe?

[Carnak]

Run the ductwork.

[framehvac]

In most areas they run the duct work it is code in wv we use the walls & pan floor joists.I would just run the duct work if I was you.

[DocHVAC]

If you don't know how to install an HRV system stay away from them and hire somebody who knows how, this is why HRVs get a bad rap, so called professionals installing who have not a clue as to what they are doing. Do your self and your customers a favor and take a course. As far as panning joists he is talking HRVs not heating, HRVs are low CFM appliances and should be installed using solid piping and I mean solid, which would be galvinized piping no flex, except for the final hook up and the piping to the outside.

[Edited by DocHVAC on 01-29-2005 at 02:12 PM]

[khc]

Stay away from flex all together. Use solid pipe and insulate pipe to and from exterior. Flex just sags with condensation build up. Any you guys believe in fully ducting or just using the simplfied method.

[DocHVAC]

khc-If you do use solid pipe to the exterior it should be insulated, sometimes there is not enough room to insulate.

[khc]

Sorry Doc I am Missing your point. When might it not be possible to insulate around the pipe? Better location maybe? That pipe must be insulated and have a vapour barrier regardless.

[DocHVAC]

khc,
A "properly" installed insulated flex pipe serves those purposes to a tee.

[Carnak]

I typically ran all the inside ducts in sealed galvanized and used short runs of insulated flex to/from the outside.

Would use wall stack or slightly flattened 4 inch round in a 2x4 wall.

Had a problem only once with the flex, was a bad batch and the HO did not keep the inlet clean. Intake flex collapsed.