Questions on replacing filtrol expansion tank

Jon_G

Hi folks, having some problems with a small room in my house that is heated by a hydronic system. A while ago, we had some work done that required shortening a section of the baseboard heat. Once everything was hooked back up, the plumber said he was having trouble filling the system and suspected the filltrol automatic fill valve as the culprit. The system is pretty old, my guess is that it was from the 80's around when the addition was built, possibly later. Specifically, its an Amtrol 110. There was a lot of corrosion on the air purger and air scoop as well. Since the start of the winter, the system has been getting more and more noisy, with audible gurgling. A few days ago, the heat completely stopped working. I suspect the pump as it didn't sound like it was circulating any water, but since I am going to be replacing it, I figured I would take care of the expansion tank, fill valve, and get a new air purger as well. The only thing I am planning on leaving is the air scoop. With that plan in mind, I have a couple questions that I hope you can help with.

First, I'm not planning on replacing the scoop because it seems like it's not a very suspect part, and because it is on the pipes pretty tightly and I don't want to risk damaging anything to remove it. Am I wrong, do these things typically need replaced after many years of service, or are they one of those parts that just keep working? Should I just go ahead and replace it or is it not much to worry about?

Second, there isn't any type of PRV between the heating system and the house. I have pretty high water pressure although admittedly I haven't thrown a gauge on it yet, but I'm guessing it's in the neighborhood of 75 psig. From the description on the 110, it says that it automatically regulates the closed system pressure, but I've also seen references in diagrams to a PRV before the filtrol valve. Is that something I should fix as well? I did find that the pressure on the tank was reading 75 psi on a tire gauge right before I shut it all off and drained it. It seems really high since the unit comes preset to 12psi from the factory, but not sure if that's because it wasn't read while the system was cold.

Tinman

The pressure on the tank has to be measured when the tank is disconnected from the system. 75# is insanely high. I hope that has been corrected? If not, shut it down and get the pressure down to 12-15#.
The picture is of an older boiler with new piping. The Caleffi 573009A combo fill valve/ backflow preventor is a great product. I also think changing from an air scoop/vent to an air separator would be well worth your time, especially since you'll be draining the system anyway. One more thing, move your pump to the supply so that its pumping away from the expansion tank (point of no pressure change). The results are tangible.

Jon_G

The old tanks and fill valve have been disconnected and the system is drained, so no danger now. Could it have been that high because of my line pressure and no prv? I thought about getting a different tank and valve but the idea of not having to redo the piping is appealing. It's not the heat for the main portions of the house so I didn't want to mess with it too much, just fix what's there. I'm not sure if I can switch to an air separator separator though as the filtro Systems seem to be designed to use the air purge, or at least that's what they show in the installation diagrams.

I'm still wondering if I need/should put an upstream PRV in before the fill valve. Is that something that's required?

Tinman

The Filtrol 110 has a fill valve (PRV, pressure reducing valve) on the top of the tank. There is never a need to have 2 PRV's on a single boiler. My suggestion is to replace the the 110 with two separate components - a new tank and a Caleffi fill valve (PRV).

Jon_G

Thanks, knowing the answer to that question is a big help. As for the component replacement, is that because the 110's and/or valves aren't very reliable or don't work that well? I'm certainly not opposed to the idea, and if I did that I could also go with http://www.supplyhouse.com/Caleffi-551028A-1-1-4-Sweat-DISCAL-Air-Separator?gclid=CL3ozvWt5soCFYkkhgodrYwAlg for the air separator and replace the air scoop correct? Any recommendation on a tank?

The current location of the supply, tank, and purge is on the outlet side of the boiler, ~3' linear. The pump is right before the boiler inlet. If I went with the califi set up and new tank, does it matter if I put the tank before or after the air separator?

Tinman

Amtrol Extrol 30 tank is what I'd typically use. I never was a fan of the Filtrol 110 - too many issues IMO. The Caleffi air separators are awesome. If you follow this set up, you'll be very pleased with how much quieter and air free your system will be.

Tinman

This system less the old boiler - not my decision to keep it.

Jon_G

Perfect, thank you very much for all your help!