Hey guys new to this place but got a question that has probably been asked a thousand times on here but Im a diy guy who wants to do things the right way the first time. Just built a shop and installed 1/2 pex in the floor 6 zones of 300’ looking for info on pump size and brand. Also which controller and mixing valve u guys suggest. I’ve talked to a few people around here and I’m not comfortable with what I’ve been told. The shop is 30x50 12 foot tall 3 12’ doors insulated under and all around thanks
Pump size
- Thread starter Utvols
- Start date
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jebatty
Minister of Fire
I take it to mean that you have 6 runs of half inch pex in the floor, each being 300 feet long. Is that correct?
Yes sir you are correct. Something that I didn’t mention is it will be heated with a H2 hardy owb.
jebatty
Minister of Fire
What you really need to know is how many btuH you need to maintain the air temperature you want in your shop, which means you need a heat loss calculation. Approaching this backwards, if the assumptions are 1) a flow rate through each loop at 0.5 gpm, or 3 gpm total, and 2) a 20F temp drop between supply water to the loops and return water, 3) then the total btuH that would be input to your floor would 3 x 20 x 500 = 30,000 btuH.
Typical flow rates for 1/2" pex in floor are between 0.5 and 0.75 gpm. Six loops at 0.75 gpm = 4.5 gpm total. Pump head loss at this flow rate would be a little over 8 feet through the loops.
But you also have an OWB. What is the size of the piping between the boiler and the shop manifold, and what is the length of that piping round trip? Do you intend to use a single circulator to move water from the boiler, to the manifold, and return to the boiler? if not, what is your design? Sizing the boiler circulator likely will be a critical factor in the design of your entire system.
Typical flow rates for 1/2" pex in floor are between 0.5 and 0.75 gpm. Six loops at 0.75 gpm = 4.5 gpm total. Pump head loss at this flow rate would be a little over 8 feet through the loops.
But you also have an OWB. What is the size of the piping between the boiler and the shop manifold, and what is the length of that piping round trip? Do you intend to use a single circulator to move water from the boiler, to the manifold, and return to the boiler? if not, what is your design? Sizing the boiler circulator likely will be a critical factor in the design of your entire system.
jebatty
Minister of Fire
Is the Hardy H2 providing in-floor heat only for the shop? Or is it also providing heat and/or domestic hot water for structures in addition to the shop? The info on the H2 shows a rating of 120,000 btuH and equipped with a Taco 009 circulator. Is that what you have?
I thought the heating ability of in floor pex or any other type of heating was limited on how much heat it can actually give off at X temp no?
so pushing water thru a floor too fast or too slow would change the output.
at least that was my understanding on it from the explanation i got from a few people.
Feeding 6 loops pushing through one set of 3/4 pex all the way from the outdoor furnace I would guess will equal pretty low flow in the loops. You'd have to put the mixing valve in the back of the outdoor furnace and push mixed temp water in, signaling the pump with a regular thermostat.
I'd prefer to have one pump pushing full temp water through the loop to the shop (the low volume high pressure 009 would work) with a higher flow pump and mixing valve pumping the floor loops using close tees.
Then the floor loops are free to move more water instead of being throttled by the underground piping.
Just an idea.
I'd prefer to have one pump pushing full temp water through the loop to the shop (the low volume high pressure 009 would work) with a higher flow pump and mixing valve pumping the floor loops using close tees.
Then the floor loops are free to move more water instead of being throttled by the underground piping.
Just an idea.
The 009 is supplying the house coil. I had hoped to put everything in the shop for easy maintenance and installation. Plans can change but if possible I would like to size it to just be one pump I’ve looked up flows on 3/4 at max 4.6gpm if I can get by with .5gpm on the 1/2” that’s 3gpm a little more than I wanted to put on the 3/4 but it’s already under the ground and it runs under the stove. I know I have yet to figure in valve and fittings but was hopeful I could get by at least for the rest on the winter with a high flow high pressure like the tyco 11 but that why I’m on here looking for answers from the best
jebatty
Minister of Fire
A diagram of your system, showing distances and inside diameter of piping, fittings, etc. would really help getting the best design. I'm reading your posts to assume that you also have 3/4 pex feeding the house loop. Correct? 3/4 in general can be a major impediment due to its low flow capacity and high head at any more than very short distances. I think you are aware of this. What started out being a straight forward question is bringing on a few complexities.
jebatty
Minister of Fire
Also if you know, what is the supply temperature normally provided by the boiler and what is the return water temperature to the boiler from the house?
By putting everything in the shop I'm assuming you would be pulling the water in from the outdoor furnace (rather than pushing)? I'd be concerned about the pump cavitating. Especially a bigger one like an 0011.
Whatever you do (one pump or two) it runs best placed at the beginning of the loop.
170 coming out I will have to get a temp gun tomorrow to get the return temp can’t figure out how to post pic can u email me at [email protected] and I’ll send u my cell number and I can send u what u need