IFC pumps

steveoPirz

If I install IFC circulator pumps on the supply side of the boiler do I still need to install flow checks on the return?

billtwocase

no

although it would be a good idea to install one above the pump on the supply should it go bad in the future, you don't need one, until the check in the pump goes bad. I had problems with them in the past, and would rather spend a few bucks more, and install a flow check right off the bat, and install a standard pump. The IFC pump should do it without an added flow check

Sensi Jimmy

agree with Bill

Would much rather see a flow check than that little plastic IFC insert

hot_rod

maybe

it the piping rises vertically from a supply you can get ghost flow up the un-checked return pipe. The more buoyant hot water rises up the center of the pipe, cooler water falls down the side.



It would be a slow heat transfer movement , but enough to cause a zone to slowly over-heat. Use a IFC circ, with a second low-pop, spring check on the return for 100% protection. isolation valves provide for check service should one get teflon tape or other debris holding it open.



Deep thermal traps, where you pipe down first, then up to the zone can work also.



This is more common in primary secondary piping where there is circulation in the loop, that could induce some flow.



hr

tim smith

checks on returns

I vote checks on returns even with ifc pumps. It really bugs me to get a call after job done that one of our guys forgot the check valve on return & sometimes that guy was me. I have got this call so many times. It is policy to do them or a heat trap sometimes.  Would not be much of a problem with rfh or sometimes low mass rads but cast iron rads pretty much always. Tim

billtwocase

checks on the return

will do you no good with a mono-flow system. I can't say that I have found a boiler gravity feeding up the return, only a supply that had a valve that wasn't seating

hot_rod

It happens on indirect tanks

also that flow through the un-checked side can cause over-heating. Also all the new solar pump stations have "gravity gates" or checks on S&R to prevent the tank from re-radiating it's temperature back to the collector.



This article describes the causes and cures.



www.pmmag.com/Articles/Column/5110bf9d48fc7010VgnVCM100000f932a8c0____

Unknown

IFC Circulators vs Flo Checks

You asked...



Back before us pump guys put checks in circs our industry installed a flow check (spring loaded check valve) on the return line.



My opinion, the old way was the right way.  Having a check valve installed immediately after the impeller, the most turbulent flow area, is technically not correct.  Theoretically there should be as much as 8 pipe diameters of straight pipe on the outlet of a pump or circ.  And how do you bleed air between the circ and check valve when installed vertically?  And what happens if the check valve plugs up when it's installed in the pump volute?  And what if the circ with the IFC is replaced with one that does not have a built in check?



Ya,I know it is rare any of these issues occur and there are a pile of IFC circs installed and are working OK.  And the installation cost (materials and labor) are less when IFC circs are used - but...

Mark Eatherton

Is this the reason for your inquiry?

You asked this same question on another part of the forum, but phrased it differently.http://www.heatinghelp.com/forum-thread/138659/Gravity-to-pump-conversion



In your last question, you were relating it in an application whereby you were also doing DHW from the same heat source. I said YES, you should put a check on both the discharge (IFC) and the return. But if it is only doing space heat, and it is a low mass boiler, then NO, additional checks will do no good...





Can you clarify your question?



Thanks for helping us to avoid confusion...



ME

hot_rod

A the end of the day

the IFC circs solve more problems than they create, I believe. The check is easily removed if you prefer a weighted check or a check installed a bit downstream.



Funny how pumps are installed ignoring them manufacturers installation direction as far a spacing at the discharge. Circulators may well be the most abused component in piping systems



hr