I am in the process of trenching 150' of 1.25" thermopex from my home to supply the infloor tubes in my 1200 sq/ft shop. My boiler is in my house in the attached garage. I think I would like to run glycol in the infloor for the shop. Should I place a flat plate heat exchanger in the basement where the thermopex comes through the wall or should I place the heat exchanger in the shop after the the thermopex enters the building. If I installed it in the basement I think I would need more glycol ,but I would be safe from freezing. In the shop I would need much less glycol and heat less water through a exchanger. Anyone have the coorect answer?
Heat Plate question
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If you put the plate in the basement then you would have to use more antifreeze to fill the lines underground. Which is not a whole lot more for the total freeze protection.
Rob
Rob
How deep would the lines to the shop be, and how deep / well insulated would the HX be if it were at the shop end? Essentially the question to me would be whether the same conditions that made me want to run glycol in the shop would apply to the HX and lines going to the shop - if so, put the HX in the basement...
Note also that you are probably not talking a huge amount of added glycol to put the HX in the basement - I forget the exact amount of feet per gallon that your pex would take, but I suspect that you'd only be talking a few gallons (maybe about 10-15) for the lines - which isn't a huge amount, your (required) expansion tank would probably take more than that...
Gooserider
Note also that you are probably not talking a huge amount of added glycol to put the HX in the basement - I forget the exact amount of feet per gallon that your pex would take, but I suspect that you'd only be talking a few gallons (maybe about 10-15) for the lines - which isn't a huge amount, your (required) expansion tank would probably take more than that...
Gooserider
I get about 19 gallons for 300' of 1.25" ID pex if I didn't screw up the calcualtion...
3.14 (.625")(.625")x300ft X12in/ft = 4416 cu in.
4416cu in. /231 cu in /gal = 19.1 gal.
That's a few bucks worth of antifreze, but you'll get the peace of mind of not having to worry about freezing if you go to Florida for a week in January. If you pay a little extra for the underground freeze protection, maybe you can also save time/money by burying the lines more shallow?
3.14 (.625")(.625")x300ft X12in/ft = 4416 cu in.
4416cu in. /231 cu in /gal = 19.1 gal.
That's a few bucks worth of antifreze, but you'll get the peace of mind of not having to worry about freezing if you go to Florida for a week in January. If you pay a little extra for the underground freeze protection, maybe you can also save time/money by burying the lines more shallow?
Mole, your calculation looks good but the I.D. of 1-1/4" PEX is more like 1-1/16" so the volume is not much more than 80% of your 19 gallon result.
Another advantage of having the HX in the boiler room with the boiler is just for convenient maintenance. With pressure gages on each inlet and outlet you can monitor the resistance to flow over time to make sure it's not getting plugged with crud. Keep your circulator right there where it's warm and cozy for your easy inspection every time you are in there messing around. I like to keep everything where I can see it regularly. I'm less likely to forget about it that way. Nothing wrong with convenient. Seems the only difference is the price of anti-freeze (which I have no idea about)
Another advantage of having the HX in the boiler room with the boiler is just for convenient maintenance. With pressure gages on each inlet and outlet you can monitor the resistance to flow over time to make sure it's not getting plugged with crud. Keep your circulator right there where it's warm and cozy for your easy inspection every time you are in there messing around. I like to keep everything where I can see it regularly. I'm less likely to forget about it that way. Nothing wrong with convenient. Seems the only difference is the price of anti-freeze (which I have no idea about)
Hey Jim . I would put the HX in the basement . I dont see the need to waste the extra heat in the 150 feet of underground pex no matter how well its insulated . On the antifreeze end of it make sure you set up provisions so that you have a way to empty and recover as much of your systems antifreeze as possible in the event that you need to work on your system .
Webie
Webie
Thanks everyone. My thermopex will only be buried about 2 feet due to other buried lines I have to cross over. I guess I will put it in the basement and have the thermopex in the glycol. I like the added protection. I have received different opinions on how large of a plate exchanger I need to buy. With 1200 sq/ft of infloor and I want the option to add a water to air modine how big do I go. I dont want to undersize?
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