insulated pex sizing for hanging heater

i am planning on installing a coal boiler soon, and i am trying to get an idea of what supplies i will need to order.
it is going to heat my house and future garage.

The builder called today and told me they have me scheduled for april.
my garage will be 30x32 with a 12' ceiling, metal wall liners, r38 ceiling and r19 walls. the garage doors are r17.

floor heat would be nice but the builders concrete crew won't do it. and i'm not interested in pouring the slab myself.

i found this hanging heater on ebay, it is 100,000 btu. what size pex will i need to supply this? https://www.ebay.com/itm/100k-BTU-Hot-Water-Hangi ... :rk:5:pf:0

or am i better off with two smaller units?

baseboard radiators would not be able to recover quick enough i'm assuming?

would a combination of the two be better? an overhead and baseboards?

i am all new to this, all i know is hot air lol

is outdoor furnace supply the best place to get the insulated pex? not finding many other options.

thanks in advance

Scott

The first thing you need to do is figure out how much heat you need for the building including recovery heat for when you open the garage door. Then you need to figure out how long the pipe run from the boiler to your garage heater is. Only then will you be able to calculate what size pipe you need.

If you go to the outdoor wood boiler people they will tell you to use 1" PEX because that works for everything in there mind.

Whatever size it ends up being, make sure it has an oxygen barrier. This is not OWB, it is a hydronic system so you need to protect it from oxygen.

I'm not sure why you would want to use a hanging heater with a blower? In your area you should be able to find some big cast iron radiators for cheap. I would take those over a forced air system any day!

-Don

My first thought is that you should get a different concrete crew. In 2019 I am surprised there is anyone left that would refuse to pour a slab with radiant heat. If for some reason that is not an option, make sure you put foam insulation under the concrete. The builder and concrete guys will tell you that is not necessary...but hold your ground. You don't want a slab that is cold in the winter and covered with condensation on humid days.

As for the pex size, it really depends how much heat you need to get out of that heater. Spend some time and calculate the heat load of the garage.

I am with Don, some radiators would be nice and quiet compared to a forced air unit...but you would need to give up some floor space.

lincolnmania wrote: ↑

Wed. Feb. 20, 2019 1:45 pm

i am planning on installing a coal boiler soon, and i am trying to get an idea of what supplies i will need to order.
it is going to heat my house and future garage.
floor heat would be nice but the builders concrete crew won't do it. and i'm not interested in pouring the slab myself.

Find a plumbing and heating contractor to jump in and run the radiant underfloor loops for you... you could train a monkey to do the footer and slab insulation. Plumbing and Heating contractor will have a concrete guy that knows his way around radiant installs...or maybe your building contractor's concrete crew would come on board then...

Many books on radiant floors out there...Dan Holohan has one...Hydronic-Radiant-Heating-Practical for the Nonengineer

I wrote this book for people who prefer plain-English explanations of how things work. You won’t find much math in this book. No formulas. No mumbo-jumbo. What you will find are simple words of ordinary conversation, and a lot of very easy-to-follow drawings relating to hydronic radiant heating. There are also stories – lots of them! I like to tell stories about the things I’ve seen as I’ve traveled around the US, Canada and Europe, looking at hydronic radiant installations. I’ve seen installers do things the right

In the shops that I have worked in, no matter how hard you try to avoid it, you always end up working on the floor. Wether its not enough bench space or the thing yer working on is too big to fit anywhere else but the floor, your going to end up there one way or another.

Because of this the radiant slab is the best way to go. You should push for this as the other guys have stated. If that doesn't work out, the next best thing is radiators. The worst thing would be the hanging heater. Heat rises so not matter what, the shop will always "feel" cold unless that blower is running. Also with the hanging heater you get Zero radiant heat so you are totally missing out on that.

-Don

i hired an amish company. the concrete work costs much less than if i hire my own crew. i can't even get people to show up to give me estimates! i called at least 10 excavation contractors, 3 called me back, only two showed up.

i can't afford to make many changes. and i need to get this garage up and running. i got personal cars falling apart and unfinished cars at the old shop from the car forum guys. only reason i got this is because a family member left me the funds in his will. right now i'm working on the ground.

can't afford to hire a plumber to consult me. would not know who to call anyway. going to do my own boiler install. cast iron radiators i can do.

once i get the land survey done in 2 weeks then i might call them up and ask them about if there is any way i could install the pex then they pour the slab. i did not go that route......do i need wire mesh in the slab to tie the pex to? because i did not order mesh i ordered the fiberglass mesh that gets mixed into the concrete and a vapor barrier.


the furnace man got drunk the day my dad ripped out the coal furnace in 1971 and never showed up. Dad installed the furnace and the tank and the duct work himself. a week later this "furnace man" stops by and wants to install the furnace and dad told him "it's been installed" so this guy wants to see......he said to dad "it looks like some shoemaker installed it" Dad said yea that shoemaker was me. now get out of my house!

insulation under the slab sounds ok, but how the heck is foam going to hold up under a 6" slab? won't the slab crack? i'm a mechanic not a builder. that's like 1000 bucks if i need 2" foam sheets. i plan on having at least one lift.

i'm not so much worried about the electric bill if i gotta move some air with fans. right now electric bill is over 200 a month because of running the furnace fan 24/7 and the blower on the coal stove 24/7 and the electric water heater. i won't have those big draws with a boiler.
mom don't want radiators in her part of the house, and there is no way to get to the exterior walls to install radiators in two of those rooms so i plan on putting a water to air heat exchanger in the furnace. i will make a zone out of the original part of the house then a zone for the addition first floor and second floor.

i have plenty of coal stoves, and it would be easy to put my alaska or the crane out in the garage but then i gotta have two coal bins and tend to two stoves, and i still would not have domestic hot water from coal. I looked into a coil for my stoker but after reading a lot of posts about it that's probably money better spent towards a boiler.

StokerDon wrote: ↑

Wed. Feb. 20, 2019 6:05 pm

In the shops that I have worked in, no matter how hard you try to avoid it, you always end up working on the floor. Wether its not enough bench space or the thing yer working on is too big to fit anywhere else but the floor, your going to end up there one way or another.

Because of this the radiant slab is the best way to go. You should push for this as the other guys have stated. If that doesn't work out, the next best thing is radiators. The worst thing would be the hanging heater. Heat rises so not matter what, the shop will always "feel" cold unless that blower is running. Also with the hanging heater you get Zero radiant heat so you are totally missing out on that.

-Don

haha i had ceiling fans at the old shop.

lincolnmania wrote: ↑

Wed. Feb. 20, 2019 6:31 pm

haha i had ceiling fans at the old shop.

You still get Zero radiant heat with this hot air stuff. That is one of the main reasons to switch to a boiler.

-Don

that was the plan up there too. i was going to get a used efm boiler vessel and a base from steve once the heat exchanger went on the hot air unit. we had gotten that efm af-150 for free in 2006. before that we heated the shop with a sunbeam octopus furnace. i gotta do some work up there this weekend, i'll have to check on the old thing, i'll bet it's neglected. they heat the living spaces up there with propane now. they gave me the hand fed coal stoves, i keep them there because i have 3 stokers in storage here lol.

Used hot water radiators will provide you with plenty of thermal mass and the heat radiates from them as an electromagnetic force warming you and everything around you as a result. Scorched air drifts up and stay up until it cools and sinks.

You can line all three walls with them and simply have a single cool water return to the insulated tubing from the very last radiator.

You just have to plan on how soon you want to heat the garage in the late summer as the slab will be a heat sink for you and hold heat as long as you properly insulate it around the foundation and install a vapor barrier as the first thing that contacts the ground before you lay down any reflective insulation board before you lay down any reinforcing mesh or rebar.

I tried to find a picture of the piping in my garage floor, haven’t found them yet. This is the only one I’ve found so far. This is the 1st driveway we started. I put 1” blue styrofoam down first in the garage then the wire. I wish I would have used it outside under the driveways and the sidewalks. I used Vanguard 1/2” polybutylene fastened on 12” centers. The garage was done in 1990 and the driveways in 1994. I could get the piping in 1000’ rolls, so no joints in the concrete. And as a bonus, there are no cracks in the garage floor 24’x40’. I believe because of the tubing in the concrete. You could do the install yourself. Divide the garage into 2 or 3 loops, and bring the tubing up above floor and mark where the loops are. Dennis

insulation under the slab sounds ok, but how the heck is foam going to hold up under a 6" slab? won't the slab crack? i'm a mechanic not a builder. that's like 1000 bucks if i need 2" foam sheets. i plan on having at least one lift.

If the concrete cracks, it is almost always due to poor site prep...not the use of foam. The compression strength of Dow Blue board is 25 pounds per square inch....3600 pounds per square foot. You are not going to put anything in your garage that is going to be a problem for those figures. Remember, your reinforced concrete slab spreads out the weight. Here are some pictures of a shop that a friend of mine recently put up. They fill it with loaders and loaded tractor trailers without blinking an eye.

DIY site will get you supplies and layouts...
https://www.radiantec.com/installation-manuals/in ... r-heating/

Don't be skerered...stand yer ground...get that radiant floor...life is too short for any do over on this one!