ghosting with new IFC'S?

trl14

Only had 10mins to look at service call this weekend hoping to find something obvious but no luck. Homeowner had new system installed a couple of years ago Ultra boiler 5 zones with 007ifc's on return. Homeowner noticed that with a domestic call this summer he was getting residual heat into one of the livngroom zones. He took the project upon himself and replaced a IFC and the problem seemed to go away for a week, but now he has ghosting in 3 other zones and the one zone that had the ifc replaced in is fine. Is it really possible the other 3 ifc's failed together? on city water and the boiler installation looks very clean as if the installer knew what he was doing. Any suggestions out there? or Should I plan on 3 new flow checks? Thanks in advance!!!

Jean-David Beyer

I have an Ultra 3...

I got an Ultra 3 boiler this May with three zones. This means four circulators. It is piped primary/secondary except for the DHW that is just tied across the supply and return from the boiler. So far, it runs only for domestic hot water although if the thermostats in the house called for heat, the circulators would run. The contractor and I tested that before they left. We even diddled the outdoor reset and warm water shutdown to get it to fire and send warm water into the two heating zones.



The circulators for the two heating zones and the DHW are all Taco 007-IFC. The boiler circulator (the one in the primary loop) is a straight 007 in the return to the boiler. In the supply from the boiler, after the pressure relief valve and the T that goes off to the DHW, is a 1 1/4" Taco FloCheck. The IFCs are on the supply to the heating zones as shown in the W-M manual. The IFC on the DHW is on the return, also as shown in the W-M manual.



We noticed no spurious heating in the zones not calling for heat. Now since it is my new toy, I have been watching what it does. When it heats DHW, the pipes to the indirect hot water heater get hot as expected (limit is set to 180F +|- 5, but it recovers so fast to 120F that I have not seen the boiler get past 170F.



When that is going on, the FloCheck gets quite hot, though it does not burn me. Up at the closely spaced Ts, the pipe gets warm, like 80F or so. So I suppose there is some little convection backwards up the return pipe, through the 007 and across the closely spaced Ts. I do not know if there is any flow backwards through the FloCheck, but there probably is not.



Now I do not suppose I would get a lot of ghost flow to the downstairs zone because there is about a six foot drop from the horizontal pipe with the closely spaced Ts in it to where the five 1/2 inch tubes enter the floor on one side, and also a six foot rise from the floor where the 1 inch return line comes back up -- they act as a trap.



But I would expect ghosting upstairs if there were some, and I have specifically checked that and found none. Now maybe this is because that big FloCheck is in there and it will open only if the boiler circulator comes on. In other words there is no real way that a DHW call could get into the heating zones unless that FloCheck were open.



Which inspires this question: if the FloCheck is bad, or if someone opened it by turning the knob on top, you could get this problem.



OTOH, the valve in the 007-IFC is a pretty simple gizmo and I do not see why it should fail soon, though I could imagine getting one bad from new. They just pop out so you should be able to replace the valve easier and cheaper than replacing the entire pump. If you can get the replacement part.

trl14

re:

I have changed the check valves before and you are right that it is a simple task, but to have 3 of them fail at the same time just would seem nearly impossible and was just wondering if anybody may have a similiar issue? This was not done primary/secondary. I usually pipe my modcons p/s but wasnt sure on the ultra as I have not installed one before. they did pipe a bypass with a flocheck also. So it apprears to be piped correctly but getting a lot of flow thru  three zones when there is a domestic call or one of the other heat calls?

Jean-David Beyer

Primary-Secondary

My Ultra 3 boiler manual is pretty firm about using Primary-Secondary plumbing, and I just looked up the manual for the Ultra 2 and it is the same. For the 80K BTU/hr model, the heat exchanger holds only about 3 quarts of water, so you absolutely must ensure enough flow through there to keep it from overheating (maybe from cracking or melting -- I would not know). I seem to remember that you must keep about 6 gallons per minute going through the thing whenever it is firing. Maybe you could find another way to determine the flow rate required for your model and to get it. 



Too much seems to be made of the difficulty of running p|s piping. I am not a professional, but I watched the pros put in my system and it could not have taken one plumber over 15 minutes to make the closely spaced Ts out of 1 1/4" copper tubing and install the circulator. And then you do not need to worry about the interactions between the flow in the heating loops and the primary loop through the heat exchanger. And the circulator for the primary loop comes with the boiler, so in one sense it is free. For the smaller models, it is a Taco 007 and for the larger models it is a Taco 0014.



In any case, if you look at page 16 of the Ultra 2 Boiler Manual (I am assuming you have an Ultra 2, since you say it is several years old) you will see how my Ultra 3 is done (except that the DHW has the circulator in the return from the DHW instead of the supply). And we can talk about the same thing. The main difference between the diagram and my installation is that the circulators for the zones are IFC; only the boiler circulator is the plain model. So there is a big (1 1/4") FloCheck valve in the supply just above the pressure relief valve and the T going out to the DHW. And if that flow-check is missing, or open (stuck, or because someone opened it by turning the knob on top), you could get the symptoms you describe. Otherwise, unless you have some very crappy water, I do not see why those IFC valves should go bad at the same time so soon after getting them installed.

Mark Eatherton

The problem with IFC's...

The spring set on these little check valves are extremely weak so as not to severely affect the GPM and head capacity of the circulator. They were never really intended to act as a true "flow check", only to act as a back flow preventer.



If you have two or more pumps, and they are facing each other, and only one of those pumps is ever on at the same time, then the check valves work just great.



If you have numerous pumps in parallel, and they are of different size, you can expect ghost flow. Or, if you have a large volume of stored hot water (DHW side arm) and system distribution pumping without control valves (large cast iron radiators) you can expect ghost flow as gravity takes over and bypasses the weak springed check valve.



If in doubt, go for either a weighted flow check, or a true spring check. I have seen swing check valves bypass due to gravity considerations, hence I don't recommend their use as a flow check.



I have seen a check valve out of a DHW recirc pump on an apartment complex that had wire drawn marks on its seat, and it was screaming like a Banshee.



Applied properly, they work great. Improperly applied, they create problems.



Even P/S piping, if improlerly applied will result in unwanted flows. And again, it has to do with gravity, which if it is a potential, it WILL happen, so care should be taken to prevent it.



Otherwise, you will get the call, "I just got out of the shower, and was walking back to the bedroom, and I can feel heat coming from the radiators, and it is 90 degrees outside. Is this normal??"







HTH



ME

Jean-David Beyer

I think that is why...

"They were never really intended to act as a true "flow check", only to act as a back flow preventer."



I think that is why they have IFC circulators in the heating zones of my system, and in the indirect DHW. And also why they have that big FloCheck in the primary loop going to the closely spaced Ts. That way, if there is a call from the indirect water heater, the circulator in the primary loop is off (controlled by the control board in the boiler) and the one in the DHW loop is on. The FloCheck is closed. And for there to be flow between the boiler and the hot water heater when the system is heating the house, the hot water would have to drop about a foot to enter the heater, drop more than three feet throught the heater, and rise about 4 feet, then go through the circulator and its weak-spring IFC back to the boiler where the boiler circulator is exerting pressure to prevent that (hence the IFC in the DHW loop).



So my guess is that the O.P. has either a missing Flow Check, a Flow Check that is manually opened, or something like that. I do not know how his system is piped, but he said it is not P-S as required by Weil McLain. It does not mean it cannot work, but it is not clear there is a real working FloCheck in there in the right place.