Print

[gainerspot]

First off, Thanks for all the help on this forum. 
I am getting a P&M 2840; the spot I plan on putting it will be about ~175 feet away from the house and about 12-15 feet higher than the crawlspace I will run it through.  I am probably going to get logstor.  I will be heating DHW and water to air exchanger.   Next year will add a green house on a second pump.
OWB, to 20 plate exchanger, water to air exchanger, pump, back to the OWB.  I will have a manual bypass for the air to water exchanger.
I was planning on hooking the pump up on the return line.  Taco 009 (35 feet head) because of the elevation back to the OWB.  I was also considering running the pump as an on demand for when the heat was needed, mainly because I live in Tennessee and the cold days are not as often or as long. 
I just want to make sure that I am going about it the right way. 

[RSI]

The pump should not be on the return line. Elevation will not make a difference. Only time it really matters is if the boiler is lower than the house.

The head rating does not have a lot to do with the elevation. It is the restriction in the system that it applies to.

With Logstor I would not use a 009 pump. Depending on the BTU load, I would either use a 0015 or a 0011. (0015 is the smaller pump of the two)

[Scott7m]

The pump should not be on the return line. Elevation will not make a difference. Only time it really matters is if the boiler is lower than the house.

The head rating does not have a lot to do with the elevation. It is the restriction in the system that it applies to.

With Logstor I would not use a 009 pump. Depending on the BTU load, I would either use a 0015 or a 0011. (0015 is the smaller pump of the two)

 

[gainerspot]

 :bash:I bet that sounded stupid when you read it. But I guess I was over thinking it. I figured the hydrostatic pressure would be enough pressure to move the water down and the suction of the circulator would pick up the rest.  I guess I also forgot to mention that the pump would be under the house not at the OWB.
As for BTU load I have no idea how to calculate that. I have read post on here of people doing the math but I couldn't follow it. When I get back home it a few days I will try to figure that out. I am clueless on head. I always thought it was how high it could move the fluid.  Would I be ok with having the pump in the crawl space?

Scott I seen on another post that u sell logstor and the closest person to me on here.  I will get in contact with you when I get to that point. It will be 200-300 feet depending on where the green house wants to call home.

[RSI]

The elevation doesn't matter because the water is in a loop. If you disconnect the return line it will drain the boiler if it is 15' above the lowest point. (assuming the line was below the water level in the boiler)

The head rating is how high the pump could lift the water but in a boiler system there is no lift since the water self levels.

The circulators are designed to be used in pressurized systems. On an open system they work fine as long as they never have negative pressure on the inlet. Putting on the return would result in negative pressure. In your case with the elevation you could put it anywhere before any heat exchangers.

[Jwood]

I'm thinking with the price of logstor the greenhouse would  like to be at 200ft

[Jwood]

Just above the lowest place in you loop mounted vertically sounds good don't it?

[RSI]

Just above the lowest place in you loop mounted vertically sounds good don't it?

That is fine on a system where it is down hill quite a bit. If it is fairly level you might not get enough gravity flow to keep up to the system flow. The pipe needs to supply the max gpm that the system will use. Otherwise it will be pulling vacuum.

It is safest to just put it at the boiler where you have no restriction before the pump. You could test it by disconnecting the pipe from the pump and see how many gpm you get out of the pipe. If it is less than will be flowing with the pump in the loop running, it should be moved to the boiler.

[Jwood]

Makes sense the way you explained it RSI

[slimjim]

The circulator is the weak link in the system, use Isolation flanges on both sides of the circ and place it where it is easy to get at and keep a spare on the shelf for that severely cold night in january when it WILL die at 2 AM on a saturday night after the New Year's Eve party

[Jwood]

Where are yours mounted slim?

[slimjim]

In my basement where I keep a good light bulb and a 5/8 and 11/16 wrench along with a phillips screwdriver

[Jwood]

That's just where I have seen most, I've seen them on the boiler to I wouldnt want to change one in the dark and cold and might as well add blizzard to those two!

[slimjim]

That is allways when it happens! Don't forget 2AM on a saturday after a good night of partying.

[Jwood]

And you can't find your boots and the light bulb out there burned out or your flashlight batteries are dead. There are so many scenarios that could happen for me the worst possible one is the one that will happen.