Retrofit of central heat to Hydronic.

[Nobodybusiness]

How effective/ efficient are the underfloor pex tubing radiant heat methods compared to ducted heat?

In other words would it make sense to retrofit a home with under floor radiant heating or just continue with ducted heat?

 

[peakbagger]

I am missing something, is the comparison between hydronic radiant heat and electric radiant heat? In that case its very dependent on your source of hot water versus electricity. If electricity is "free" from solar and water requires oil or gas then electric in floor radiant will be the best choice for you situation. In my case hot water is "free" as I burn wood in a wood boiler and have thermal storage. My power is also "free" but given my high heating load in NH, I would run out of surplus and have to buy power again so I burn wood that I need to cut down for other reasons (woodlot management).

Unless its new construction, radiant of either type is expensive to install. I would need to guess on your ducted system. If its a tight new or modern install with the ducts inside the conditioned space, or old school ducting strung like spaghetti in the unconditioned attic frequently. In the case of old school ducts, the solution may be to abandon the ducts and seal the registers and go with a couple of minispits. If you have modern duct inside conditioned spaces, you could install minisplits with duct mounted coils and gain some efficiency over conventional fixed or two speed heat pump.

BTW, in floor radiant is not your only option, John Seigenthaler the hydronics "guru" is a big fan of low temp radiant panel heaters or hidden radiant in walls and ceilings. They can use lower temperature supply water than in most in floor systems as drywall has a much lower R value than a subfloor with flooring on top. The trade off is in NC you need AC and have humidity so radiant cooling is lot more problematical system. Its starting to get done in very tight homes designed for it but in most cases, terminal units with air handlers (that look like the inside unit to mini split with drain pans are used for AC. The nice thing with terminal units is that they are fed by either cold water lines or in higher end systems refrigerants (in a VRF type system). water or refrigerant can move the same amount of heating or cooling with lot a less space than ducts so transmission loss is much lower and a no brainer if old style ducts are used.

It all comes down to HVAC is very much of custom solution for every home and region so what is the right fit in NC in home to be built is lot different than an existing older home. The new Taco air source monoblock systems are also a radiant source option that is going to be hard to beat. If I had to guess I think the Air source heat pump options with a mix of inwall or ceiling low temp hydronic radiant and some terminal units for cooling is going to be the lowest cost heating option to operate in the long run for much of the country but not a great option for high heating areas like mine. My guess is the air source heat pumps get replaced with geothermal unit.

 

[Nobodybusiness]

I am missing something, is the comparison between hydronic radiant heat and electric radiant heat?

No.

Trying to figure out if retrofitting radiant water heat under floor joist on existing house is as effective as Central heat.

It would be a retrofit so no tubing above floor.

It would be run along the Joist underneath.

This is more of a delivery question than a source of heat.

 

[OzSolar]

How effective/ efficient are the underfloor pex tubing radiant heat methods compared to in floor radiant heat?

In other words would it make sense to retrofit a home with under floor radiant heating or just continue with ducted heat?

"Borderline to not at all" would be my 2 cents.

Around 15 years ago I did a few "staple up" jobs in new construction with full basements so there was pretty easy access My knowledge base is certainly dated today but was hasn't changed is that it was labor intensive and there were some areas we just couldn't get to and that was new construction. Retrofitting it into floor joists with wiring and plumbing would super challenging to nearly impossible.

Wood is a pretty good insulator so you have to use much warmer temps than with a concrete slab. ~125f vs 95f is my memory. If your floors are carpeted if would be even worse. YMMV

 

[Nobodybusiness]

"Borderline to not at all" would be my 2 cents.

Around 15 years ago I did a few "staple up" jobs in new construction with full basements so there was pretty easy access My knowledge base is certainly dated today but was hasn't changed is that it was labor intensive and there were some areas we just couldn't get to and that was new construction. Retrofitting it into floor joists with wiring and plumbing would super challenging to nearly impossible.

Wood is a pretty good insulator so you have to use much warmer temps than with a concrete slab. ~125f vs 95f is my memory. If your floors are carpeted if would be even worse. YMMV

That’s what I figured.

I was asking for my son as he bought and old house and is currently fixing it up.

He was asking about the viability of doing that instead of replacing both Heatpumps.

 

[OzSolar]

That’s what I figured.

I was asking for my son as he bought and old house and is currently fixing it up.

He was asking about the viability of doing that instead of replacing both Heatpumps.

What would make a lot of sense is to use the electric mat in the bathrooms and other tiled areas if they are doing new flooring.

 

[Nobodybusiness]

What would make a lot of sense is to use the electric mat in the bathrooms and other tiled areas if they are doing new flooring.

They are replacing all the flooring.
I told him about the electric mat for tiles.

I think he plans on doing floating floor in the rest of the house.
Some kind of Faux wood / stone flooring?

Not sure if you can use electric matting under floating floor or not??

 

[Sky-HHI]

I can't comment on the cost of retrofitting, but we built a house in Colorado and installed infloor hot water heating while it was being built. The cost was twice the expence and force air heating system. That said , the infloor heating is the best system for heating. If you set the temp at 72 then everything in the house is around 72. The bed, furiture, the tile and wood floring, your clothes . everything get heated about the same. Unlike hot air that runs to the ceiling and then slowly heats everything below.

 

[Nobodybusiness]

I can't comment on the cost of retrofitting, but we built a house in Colorado and installed infloor hot water heating while it was being built. The cost was twice the expence and force air heating system. That said , the infloor heating is the best system for heating. If you set the temp at 72 then everything in the house is around 72. The bed, furiture, the tile and wood floring, your clothes . everything get heated about the same. Unlike hot air that runs to the ceiling and then slowly heats everything below.

You do get that benefit for sure.

My son is doing his house and was asking.

I don’t think he will have the budget to do loop heating above floor with some type of cement over it.

He was asking about the staple up jobs that Ozsolar mentioned.

 

[OzSolar]

They are replacing all the flooring.
I told him about the electric mat for tiles.

I think he plans on doing floating floor in the rest of the house.
Some kind of Faux wood / stone flooring?

Not sure if you can use electric matting under floating floor or not??

There's an electric product for pretty much every application when I looked last year. Home Depot had quite the selection along with plenty of useful information on thier website.