In floor or mini split??

[zombiescustoms]

Embarking on my new garage project and was looking for some one in the Mid-Atlantic area for some incite on either radiant floor heat or a mini split heat- A/C system, I have gotten a quote of around $1600 from Radiantec, for everything but the HW heater, but from what I read a mini split is about the same cost with the added bonus of A/C, Any one have input??

 

[csmende]

I'm curious about this exact thing as well. I'm in Kansas City, so get all four seasons with reasonable humidity in the summer. I have an existing 30x50 steel shed with a gravel floor. No insulation anywhere (yet), and have been collecting quotes for a pad to start the project. I have a quote for $1/sqft to add tubing and manifolds to the flatwork.

Things I'm curious about the first quote I've received:
1) the contractor spoke of an insulated vapor barrier. Is there an alternative to polystyrene foam, or is he cutting corners?
2) his design includes zip-tying the pex tubing to the rebar in the pad (seems like the only option, since there is no foam to staple them to. Is this reasonable?

Reading here for a few days I've got the same question as zombiecustoms above -- why not a mini-split so I can also have A/C in the summer?

http://www.cityrating.com/citytemperature.asp?City=Kansas+City

 

[bimmer1980]

keep in mind the one of the key benefits to the radiant floor heat is that it warms the floor and radiates upward. Meaning this, your feet are warm and therefor the rest of you feels warm. With the minisplits you would be blowing warm air. Warm air rises, so the floor would still be cold.

I'm working on my garage and I'm thinking about using the radiant floor for the primary heat--keeping it at 40 to 60 degrees, and then using a mini-split to quickly warm it up as necessary for when I'm out working. It would also work in the summer time as AC...

remember that if you decide to skip the radiant floor heat, it is extremely hard to go back and add it... (unless you want to rip out the tube and re-pour)

 

[Dragster Racer]

If you can do like bimmer, that is the best of both worlds. I didn't go with the radiant in the shop, but did in the house and garage. My reasoning is that I would keep the shop cool when I am not using it, and bump it up when I am. This doen't work well with radiant. The comfort factor is a good one too with warm feet.
As far as insulation, I have my own opinion after putting in tubing myself:
1. The roll out stuff works well, for the contractor. It has give, and will not have voids under it even if the grade is not perfect. Pimco Pex company doen't recommend the roll out stuff at all.
2. Your best bet for insulation is the foam boards. But they are a pain to get perfect on the base. That is the route I went, and I hope that minor voids won't be an issue down the road.

 

[csmende]

I like the idea of my feet, toolbox, toolbench, etc ... all being warmed as well.

My biggest concern about the roll-out is sufficient R-factor. Any suggestions for supplies the roll-out and where I might get some stats?

 

[tdkkart]

Keep in mind that for a given space you need "X" number of btu's to heat it to a set temperature "Y" no matter what the heat source is. If you raise "Y" by 5 degrees you also have to raise "X" by a set factor. What that factor is depends on how big the space is, and how much heat it loses.
Conversely, if you can lower "Y" by 5 degrees you can also lower "X". Lowering "X" means that your costs go down, sometimes dramatically for a very small change in temp.

Now, also realize that no matter the air temp, the warmer your feet are, the warmer you will feel.

In my first winter of living with a shop with radiant floor heat I found that I was very comfortable with a thermostat setting "Y" as much as 10 degrees or more below what I used in my old shop that had forced air heat. You can figure out the rest.

Ask the contracotr what the R-value of his insulation is in a direct contact(cold on one side, hot on the other) installation. I have not yet heard anyone that could give me that answer on the foil or bubble type products.
Accept no less than a "real" R10 under your floor. So far the only accepted way to get that is with 2" of poly foam board.

 

[thammel]

I have a new 28 x 32. I'm still wrapping it up but did put in the pex. First the gravel, then 6 mil vapor barrier, then 2" thick foam boards. I stapled the pex to the insulation boards then had wire mesh put down. I have three loops of about 260' each 1/2" pex. I'm planning on a mini split along with the tubing. My thought was I had one shot to put in the pex and I didn't want to have any future regrets. So I think I'll do the mini split first and then the boiler sometime in the future. I figure that minimizing heat loss is always a good thing so the insulation board has to help. If you go through the calculations on the PSI loading on the board due to 6" thick concrete, you'll be astounded at how little it is. Back to the mini split. I think it's by far the most economical. Also, I've not had good luck getting hvac places to give me quotes on a gas furnace and ac for the garage. They must not be hurting for business.

I know I can order a mini split on-line and do the install myself and will have a great result. I'm figuring somewhere in the vicinity of 2K$ for the system.

Tom