grundfos ifc's pump problems

Mark Eatherton

If you have enough vertical height above the heat source, and the heat source is not properly/completely trapped, you WILL get forward thermal siphon occurring, which can cause your scenario.

You MIGHT want to look at the supply side issues to see if you can stop the heat ghost flowing from the source. Even after you add a flow check, it is possible to have one pipe flow (up the center and down the sides) that can be of issue.

ME

chris_93

Grundfos IFC issues

Hi, been experiencing problems on two jobs now that ifc pumps were used. Both jobs have air handlers that will come on w/o pump running.
First house pumps have beeen in about 7 months.
Second house less than two months.
Going to gut the ifc from the pumps and install flo controls.
Anyone else having problems???
thanks,
mike

Unknown

Not yet,

but I use Taco now.
Are they coming-out from the casting, or just plain sticking-open?
Taco machines a groove to help hold them in.

Dave

hot_rod

check both S&R

as Mark mentioned.

I've also seen them with threads of teflon tape, solder balls and copper shavings holding them open a small amount.

If both sides are checked and you still get ghost flow remove the pump and check the check.

Were they soldered against? They could have been distorted by overheating.

hr

billtwocase

Mike

sorry- repost

billtwocase

Mike

I've been there done that with the built in check valves. Garbage JMO. Seems like you are back there cleaning out the plastic check valve, etc, and end up putting in the old reliable swetcheck. I just do it right from the start. They all have good intentions, untill we have to eat the labor to make it right. peace

chris_93

we've been there twice already to clean and check

These pumps are installed on the supply. I used isoflanges on either side of pumps.
I can't believe how "cheesy" the design of the flo check is- piece of plastic and crappy little spring. I've used dozens of these pumps. I hope this isn't going to be a nightmare for me in the near future. I definitely won't be using them anymore.

kpc_73

never had....

an issue w/ the 15-58 IFC... now sweat checks had a load of issues. Might just be a bad one(s)... did you swap it out? kpc

billtwocase

swetchecks

The only issue i've ever had with them was years back Taco was using a rubber seat for a short time. If I had known to take them apart to find a rubber washer, wouldn't have soldered them while in the closed position. Anyone run into them mid-late 80's? Needless to say they went back to brass weight. peace

Darrell_4

I've modified some that were giving me trouble by going to the local true value hardware store and getting a bag of 5/16 stainless springs. you get ten in a bag for a buck or two. swap the wimpy spring in the check valve for the beefier one and it will tend to stop most ghost flow issues.

Mark Eatherton

How's it piped and pumped?

If you have pumps in parallel, the check valve will do NO good. Not sure if even a sweat check would do any good.

I wouldn't throw the baby out with the bath water until you're sure what the cause is...

Got pictures and drawings?

ME

hot_rod

a Y strainer or dirt separator

might help keep the crud out of the checks?

It's not the fault of the pump or check that debris keeps getting into them.

hr

hot_rod

the springs have a low pop pressure

I think 1/2 psi, so they can be used with variable speed, injection mixing, etc and to allow them to open when the pump speed is very low. This could be the case with variable speed or with the pump set on speed one.

I think, early on tekmar had a spec on the pop pressure of checks used with injection mixing, as high spring tension caused the pumps to surge, as the had to ramp up the speed so high to open the check. The temperature would spike and overshoot and the pump tried to ramp down to low, then surge higher to pop the check open.

We recently had a similar issue with the solar pump stations that have intergrel check in the iso valves. When we set the control in the variable speed mode, the 30% speed range, with a Wilo Star 16, would not allow the check to open. We had to set the control to a higher minimun to assure the checks opened, especially with cold thick glycol.

hr

chris_93

pic

Both these boilers are piped pumping away using speedy headers. All pumps are on speed 2. Here's a pic of one of the boilers. Existing boiler, on 6000 sf house. One of the supply's in the pic feeds a remote radiant manifold. I have pulled the checks out twice and found nothing in them. It seems like the spring is just not strong enough. Also they only have a plastic to plastic seat. Not thrilled with that either.

billtwocase

mike

The piping looks ok from what I could see,a better angle would help, but is this a new customer that you picked up to straighten out their problems? I see the wrong pitch on the smoke pipe from what looks to be a Bock water heater, no screws in any joints, and the wiring is so illegal. I'm sure you are trying to make it right for them, but i'd personally spend some time on the safety issues as well. Don't take this the wrong way. peace

chris_93

this was a pic before it was finished

Hey Bill,
THis job was an extension to an existing house. We cleaned up a mess on the existing boiler. The pic is while it was under construction. Smoke pipe was out to clean the chimney and elect rewired the boiler. Appreciate the feedback. thanks,
mike

Mark Eatherton

It's gravity ghost flow...

I'm just guessing here, but if this home is two stories, you have roughly 16 feet of vertical height between your boiler and the FCU's. It's nit just the lighter water wanting to rise that is working against you, but also the heavier denser water that the FCU's is generating causing a major convective action that the itty bitty spring in the IFC can't cover. As I stated previously, I don;t think the design was for the check ball to stop the potential of gravity thermosiphon as much as it its to keep the water from being drawn or forced backwards through the pump. You're going to need to do one of two things. You could put a zone valve at the FCU serving the circuit, but that would require a transformer/relay to be set etc, but it is guaranteed to stop the thermo siphon that is occurring without paying a huge price in the area of flow.

The other alternative is to put spring loaded check valves on the supply and the return. This is going to cause more restriction and will affect your normal flow patterns.

The third alternative would be to pipe some real deep traps on both the supply and return, but I have seen these overcome by gravity before, so I can't recommend it.

I really don't think your luck would have been any better with another manufacturers IFC type of pump. Don't toss the Gfos pumps. They're fine.

ME

chris_93

Hey Mark,
you are correct the home is two stories, with air handler in the attic. THere is at least 20' of vertical rise. I went there this morning and installed spring checks above the pumps. I ran 1" to all the air handlers with uponor fittings. Approx 100' of pipe S&R on the longest loop. So i should be in tolerance as far as head and gpms.
I'm not giving up on the pumps, just not going to use IFC's anymore. I was a little misrepresented by my wholesaler as to what the IFC can do. And after i took them apart, surpised how they work at all!!
Thanks for the feedback,
Mike

Unknown

If the thermosiphon is this strong, maybe he can take the pumps out and use pumpless zone valves

Mark, do you know of any good "thermosiphon calculators" out there? say for figuring out pressure differentials for different types of scenarios?

Mark Eatherton

Sorry Rob...

Can't help you there. I am sure it is calcuable, but that math is out of my arena.

That would b a good Siggy or Bean or Geoff equation. Maybe even take all three of them :-)

ME

Unknown

But......

There is much , much less of a chance crud will get stuck in a weighted flow valve . We had to stop using internal check circs for this reason . Flushing the system with a cleaner is always a good idea , but most do not ( us included ) . A good purge with hot water was all that was needed for weighted checks . I can count on one hand the ghost flow problems we had using them .

Bob Bona_4

I've

seen both weighted checks and IFC's get clogged. It seems stray teflon tape is a major player.

IMO, if there's junk in the system, there's junk in the system that needs to be addressed-it's not fault of the flow control device. Mike, I don't see the IFC's as cheesy, all they have to do is stop flow. Taco and Grun both use the same basic design, wouldn't surprise me if they came from the same vendor.