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[netwerx-r-us]

Im getting ready to make the plunge and buy a OWB , I plan on locating it centrally in between the house and greenhouse I will be heating , 180 ft from greenhouse and 150 from house , 2 separate runs /lines

at the house side  I am planning a 30 plate changer and a water to air hx 18x20 also would like to run a line to the garage , 25 ft , this is to be used for heat not 100 % of time but just when in use to knock the chill off

at the greenhouse side I m planning a 18x 20 hx heater  i would also like to run a line to my second building 40 ft away for heat ,another 18x 20 hx

my question is do these runs need to be plumbed in a series in other words hit the house first and then from there hit the garage and return to the same line  line or can a  "  T " be put in to split the 150ft  line and feed both equally 

same question for my greenhouse 180 ft run at about the  120 ft mark can i  put a T in and feed the first building and then continue to the greenhouse or do they need to be plumbed in a series hit one go in and come back out and continue to second building

thanks in advance

[muffin]

You can do either.  The danger in the series is that the drop in temperature will be to great and the main thermostatic valve will start shutting it down.  I think parallel is better, but you can probably get away with two in series, especially if they are not going to be on at the same time frequently.

[RSI]

What size pex do you plan on running? I would consider going with either 1" pex-al-pex or 1-1/4" pex. If you run in parallel you can use 1" after the split. I would run through the 30 plate before splitting it off though.
If you just use a tee, I would pump into the side fitting and out the two ends. Also put valves on both or you will not be able to get all the air out and one will probably need to be partially closed to balance the water flow.

If you do all in series instead you need to make sure nothing anywhere in the system is real restrictive or it will screwup everything. It sound like what you are running through should be fine though.

[netwerx-r-us]

very good advice , thank you , I can visualize the T on the feed side and the return side,  makes sense, the advice of the valves makes perfect sense , the issue I'm having trouble visualizing is the plate exchanger the one I'm  looking at has 3/4 ports , if i hit this first before going to both sides will this restrict the flow ?or do  need to run 3/4 lines after that ?
thanks in advance

[muffin]

very good advice , thank you , I can visualize the T on the feed side and the return side,  makes sense, the advice of the valves makes perfect sense , the issue I'm having trouble visualizing is the plate exchanger the one I'm  looking at has 3/4 ports , if i hit this first before going to both sides will this restrict the flow ?or do  need to run 3/4 lines after that ?
thanks in advance

I would put bypass valves around all exchangers.  This way you can relieve the restriction as well as control the flow a bit.

[RSI]

How big is the plate exchanger? Is it much smaller than 5x12 inches?

[netwerx-r-us]

I was planning on this particular one 175,000 BTU/hr: 30-Plate Heat Exchanger, 3/4" MNPT ports, 3" x 8", this was just for my hot water use, not to heat anything with

[RSI]

That might choke the water flow down a lot. I never use anything smaller than 5x12"

Can you find pressure drop ratings for that plate? It may work if it can handle the flow and will be similar in heat transfer to a normal 10 plate.

[netwerx-r-us]

175,000 BTU/hr: 30-Plate Heat Exchanger, 3/4" MNPT ports, 3" x 8"Design Parameters:

· Design Pressure: 435 psi
· Design Temperature: -256oF / 437oF
 
Technical Specifications:

Flow Rate: 15 GPM max.
Connections: 3/4" Male Threaded
Dimensions: 3" x 8" x 3.11"
Max BTU output: up to 175,000 BTU/hr

now there is another one similiar 4x12  with 1 inch ports , 20.00 more
150,000 BTU/hr: 10-Plate Heat Exchanger, 1" MNPT ports, 4-1/4" x 12"
Design Parameters:

· Design Pressure: 435 psi
· Design Temperature: -256oF / 437oF
 

Technical Specifications:

Flow Rate: 30 GPM max.
Connections: 1" Male Threaded
Dimensions: 4.25" x 12.12" x 1.32"
Max BTU output: up to 150,000 BTU/hr

basically I want to use it to heat my hot water , if im investing this much to heat I might as well get hot water out of the deal , Just me and the wife and 2 cats , I would like it to be able to have the ability to expand a bit just in case , I am not thinking this out right ?

[RSI]

Just because the 10 plate has 1" ports doesn't mean it will flow any better. All the plates are in parallel and that is where the restriction is. The small 30 plate says max flow 15 GPM but what is the pressure drop? That is what you need to know.