My friend is setting up his new Tarm in his garage to feed heat to his existing oil system in his house and wants to know what to use. The plumber recommended 3/4 and the Tarm is built for much larger pipe. Will 3/4 inch pipe be enough?
size of underground piping
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tire man said:
funny, we're doing an install just like this now.
i'm an old school conservative, when it comes to boiler/baseboard/pipe sizing. i learned long ago, that the supply-house 'engineers' performing heat-loss/heat-gain calculations free for the contractor are employed by whom?
right-o.....
they add, in many cases, up to 50% MORE baseboard than you really need. I've seen it for 25 yrs.
it behooves them to upsell boilers & components. how else do they make money?
example: my own house- high-velocity A/C (spacepak) called for 52 outlets...i put in 26...works like a champ.
that being said, we normally run 1" pex tubing between add-on boilers & existing house boiler. you can easily (& for a lot less $) compensate for friction loss by upsizing the pump... a taco 008, or 009, depending on flow/head situations is more than adequate.
3/4"? not a good idea
It best to size the pipe to the amount of energy, in your case BTU's it needs to transport. Plenty of places to find tables or formulas to determine pipe size.
what you need to know first off, is how much heat, energy, BTus are required in the shop. then the distance and type of piping.
Yes you can fudge little and upsize pumps to overcome pipe sizing. it will cost more for the pump, and you risk running high velocity (speed) through the tube and fittings. possibly higher operating cost, and shorter pump life if it runs off it's curve.
With a small off the shelf, inexpensive wet rotor circulator, like a Grundfos 15-58 3/4 pex can easily move 40,000 BTU/ hour over 100 of length. 1" pex about 65,000.
what you need to know first off, is how much heat, energy, BTus are required in the shop. then the distance and type of piping.
Yes you can fudge little and upsize pumps to overcome pipe sizing. it will cost more for the pump, and you risk running high velocity (speed) through the tube and fittings. possibly higher operating cost, and shorter pump life if it runs off it's curve.
With a small off the shelf, inexpensive wet rotor circulator, like a Grundfos 15-58 3/4 pex can easily move 40,000 BTU/ hour over 100 of length. 1" pex about 65,000.
1" pex is pretty much the bare minimum for underground piping. Even then, you can't transport much heat over any large distance (remember, the piping distance is more than double the physical distance between the two structures, or the structure and boiler).
I'm doing an install now with two buildings that are 190 feet apart, and we're running 1-1/2" piping to handle the load, using a properly-sized circulator, not a high-head (read: high electrical usage) unit.
I've talked to one guy who had a wood boiler installed with too-small piping, and went the "put a big circulator on it" route to solve the problem - his electric bill ended up eclipsing the fuel savings, because the pump was so large, to overcome a poorly-chosen pipe size.
To size a pipe, you need to know the distance, the amount of heat that needs to be transferred (btu's or kW), the desired temperature drop (20 degrees F for most applications), and whether the fluid will be pure water, or a water/glycol blend. Once those factors are established, the friction of the piping can be calculated for various pipe sizes, and a size which yields a reasonable friction number (called "head loss") can be chosen.
Joe
I'm doing an install now with two buildings that are 190 feet apart, and we're running 1-1/2" piping to handle the load, using a properly-sized circulator, not a high-head (read: high electrical usage) unit.
I've talked to one guy who had a wood boiler installed with too-small piping, and went the "put a big circulator on it" route to solve the problem - his electric bill ended up eclipsing the fuel savings, because the pump was so large, to overcome a poorly-chosen pipe size.
To size a pipe, you need to know the distance, the amount of heat that needs to be transferred (btu's or kW), the desired temperature drop (20 degrees F for most applications), and whether the fluid will be pure water, or a water/glycol blend. Once those factors are established, the friction of the piping can be calculated for various pipe sizes, and a size which yields a reasonable friction number (called "head loss") can be chosen.
Joe
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