pump on supply or return line

[trumpeterb]

I am still installing an eko 40, and the installation diagram that I was supplied with has 2 taco circulation pumps, both installed on the return lines...one on the main loop return, and one on the return line of the secondary loop. As I was ready to start installing these, I read the pump instructions, and they say to install the pump on the supply line after the expansion tank. I am not sure what to do, and I don't want to make a huge mistake. Any advice?

 

[Gooserider]

I am still installing an eko 40, and the installation diagram that I was supplied with has 2 taco circulation pumps, both installed on the return lines...one on the main loop return, and one on the return line of the secondary loop. As I was ready to start installing these, I read the pump instructions, and they say to install the pump on the supply line after the expansion tank. I am not sure what to do, and I don't want to make a huge mistake. Any advice?

There are a LOT of options, starting with how you choose to plumb the entire system. It would help if you could post a picture of your proposed diagram so that we can see just what you are planning - it is possible we may have some suggestions.

However for most setups the key question is where is the expansion tank? I'm not going to go into the physics and such behind it, but the point where the pressure tank attaches to your system is known as the "Point of No Pressure Change" and the standard rule of thumb is that your best pump placement is close to the tank, with minimal flow restricting hardware between the two, and pumping AWAY from the tank...

Back in the bad old days, pumps didn't like heat, and the theory was to put them on the return line to minimize the heat they were exposed to. Modern pumps have better materials that aren't heat sensitive, and it is considered far more important to maximize system pressure, and minimize the potential for cavitation by following the "pump-away" procedure.

Gooserider

 

[Tony H]

Posting a diagram of your proposed system would be a great idea
The eko 40 I am using i have the exp tank at the high point in the system on the supply side about 6' from the boiler output and the single pump in the system is on the return about 2' from the boiler in between there are 75' buried pipe 50' pex indoor a sidearm for hot water and an exchanger mounted in a gas forced air furnace. The plans were provided by the dealer and are similar to many other simple installations. The system makes tons of hot water and keeps our house plenty warm.

 

[Former Farmer]

Installing the pump after the expansion tank, fill valve, air vent is a good place. That way, if you have air in the line, the air vent will get rid of it preventing a possible air lock at the circulating pump.