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[wissel12]

I was wondering if the pump in the basement is better than on the boiler?

I'm going to put a air handler in the attic for cooling. The house is baseboard heat
currently. So I thought about putting a coil in the air handler for heating the up stairs.

What are your thoughts?

Pumping size is the next issue to get it up there??

Thanks Zack

[RSI]

It is personal preference most of the time.
I like them on the boiler because it is much easier to keep air out of the pump.

How much higher than the boiler would the new heat exchanger be? It can be done but there are issues with going up a ways. You will want a pump with a max head rating higher than the height from the top of the boiler to the heat exchanger. That way it will be able to self purge air if it gets any in the system. If you use a pump with a lower head rating, it will work fine as long as there is no air in the system. If it is real high you might want to consider pressurizing  the loop. That way you could use auto air bleeders. They won't work on an open system unless you have a restriction on the return side and a pump with a high enough head.

[wissel12]

Thanks RSI

So I could use the upstairs zone for baseboard heat. Take all the baseboards out and just run it to the
air handler.  And use the current boiler as back up for the loop.

I was going to put a heat pump in as back up.

[slimjim]

yes it's a matter of preferance, I choose the basement for easier maintenance, as long as it's below the boiler, air will not be an issue. As far as a coil in the attic it should not be done without the use of a heat exchanger in the basement as when the circ shuts down the water will drain back to the boiler, it will be a constant problem with air in the coil.

[wissel12]

So use the closed loop on the existing boiler to the air handler(two zones already). 
A plate exchanger before the existing boiler would do both?

The thermostat on the air handler would call the zone pump the for
the upstairs loop to run water to the air handler.

How does that sound?

[yoderheating]

 I never put the primary pump in the basement. Saturday I had to work on a system that I didn't install that had a pump in the home. Ended up spending two hours working the air out before I could leave.

[slimjim]

Come on Yoder, 2 hours getting air out of a non pressurized loop, If they brought in make up water between 2 ball valves in that non pressurized loop then all air can be driven back to the boiler in seconds, somebody wasn't thinking on that one.

[cranman]

I like to have the pump inside the building, as long as it is lower than the OWB. In the far North it is always nicer to service inside than out by the boiler. I've also had to replace a couple Grundfos mounted on the boilers from condensation problems as the early models weren't ventilated with those little round holes in the pump case. If you don't have the elevation in your favor, it is a different ballgame and furnace mounting is the only way to go.

[hondaracer2oo4]

Don't forget friction loss from the boiler to the pump. Could cause the pump to cavitate.

[willieG]

my pump is in the basement...250 feet form teh OWB and about 2 feet lower than the OWB.. force the air through will the garden hose as described many times here by others on intial start up. have never ever had to chase air out again, and this is year 13 for the original pump. 

[willowbk]

due to higher powers,only spot for my owf ended up being 225 from house and about 15-20 below basement.
sales men for p/m said was ok to put pump in the house. wrong, we couldnt hold prime all the time and thanks to slimjim we added 2nd pump down at owf and turned inside one down to low speed and now get a nice flow.

[Sprinter]

A lot of the pumps come with or you can add the check valve. This will hold fine, unless the system is full of debris that can foul the check. The F in the pump model is for flow check. There is a whole article on open systems and their problems when the boiler is lower than any part of the loop. A circulator can be anywhere in the system, it doesn't matter. And if it does there are other problems with the design.
I keep reading posts in regards to head referenced by water column height or elevation. When you read and select a pump from a curve chart it has NOTHING to do with elevation. Although the overall height of the loop or water column does produce atmospheric pressure the taller the column and also referred to as head in the plumbing code book, it's not the same head from friction or flow losses.
Ever read the specs on an air handler or heat exchanger or indirect water heater, and it will note the head loss in the coil or flat plate.
As Honda racer referred to before on the Taco website, there are videos explaining this and how to calculate head correctly.
I've seen some systems remedy this by simply coupling onto the overflow with a half inch pipe to the same level as the highest point in the loop. Unfortunately the pressure you read at the low point is the systems operating pressure. Not good for a boiler not designed for pressure.  20-25' of elevation is around 20-28 psi if I remember right.  But what do you do when you have problems and you've just spent 10-20 grand...

[LittleJohn]

Yoder you are correct a system can be hard to purge/vent of air, depending on design of system.

However that being said air always find the highest spot it can and stops, so having multi points to vent the air is always beneficial.

P.S. I had an issue with my garage for a while until I realized that is was just vapor locked and I vented some air and problem solved

[ecc_33]

I put my primary pump in my basement. My boiler is lower than that pump. I would guestimate around 12 feet lower. I had to bleed the pump the second day the system was running. After that all was good.