Radiant heat plumbing "upgrade" necessary?

cnm

I recently called a plumber out to troubleshoot a radiant heating system boiler that was not igniting. While he was inspecting the system, he said he found some issues that need to be addressed or the system is sure to fail. It's a 12 year old system with a Lochinvar Solution boiler that seemed to be functioning just fine last winter (we've only owned the house a year) and fired up just fine after resetting a safety switch that somehow tripped over the summer.

First thing, he says the expansion tank is "popped" and needs to be replaced. He activated the valve on top of the tank while the system was running and a bit of moisture came out. Tapping on the tank, it doesn't sound like it's full. It sounds hollow on top, solid on the bottom half. Is any moisture in the top of the tank cause for replacement? He also said it's recommended when replacing the expansion tank to replace the air eliminator, check valve and some other valve at the same time. Finally, he says that because my expansion tank is plumbed on the return side, it's working twice as hard and just replacing it without the other parts and re-plumbing it onto the supply side is asking for another failure in 6 months.

I'm not a plumber or much of a DIYer. I feel like there may be a real issue with the expansion tank and the other stuff isn't really necessary (after all, this system has functioned for 12 years plumbed as-is).

Is it standard to replace all of those parts at the same time? What's wrong with the expansion tank on the return side? There seems to be some debate on which side is better or whether it even matters?

Jamie Hall

Well, ideally the expansion tank should be piped in just upstream of the intake of the main circulating pump. It doesn't matter which side of the boiler it's on. However, if it isn't, it isn't, and it's not worth the effort of moving it unless you have to do other work. And a bit of moisture coming out of the tank when one hits the Schrader valve isn't a big deal. Nothing coming out would be. Water in a stream would be.

Perhaps you need a qualified heating contractor? Check the "Find a Contractor" tab on this site -- or just tell us where you are. We may know someone.

GroundUp

No pricing discussed here, please edit your post. As for the piping, if water comes out of the valve stem (tank must be upside down if the stem is on top?), the bladder is compromised and the tank needs replacement. Depending where the pump is located in relation to the tank, it may or may not need to move. The pump should be shortly downstream from the tank, pumping away from it. If the tank is improperly placed, that is a common reason for tanks to fail so he may very well be om the right path- do you have a picture of the system you could share? The air eliminator doesn't generally need to be replaced along with the tank but depending on its condition, it's possible

Docfletcher

$$$v cost, pricing comments are not allowed on this board. Now that I've said that, I'll tell you in my opinion, it sounds like a hose job to me. I'd find another contractor. My expansion tank in my home is also on the return side. My boiler is going on 26 years old now. I've replaced the expansion tank once in all that time. But, I'm not a pro, like you I'm a homeowner trying to watch my wallet. I'm not saying your tank is not bad, it might be. A second or even 3rd contractor is needed.

Zman

The location of the expansion tank and the system circulator does matter. If the installer of the expansion tank put in the appropriate valves, checking the tank is an easy DYI.
If you can post some pictures of all this it would help.

cnm

Oops, edited out the pricing comments.

Here are some pictures of the system ...




Let me know if you need more angles to make sense of it!

SuperJ

The Spirovent air separator is a decent piece. I wouldn't get rid of it unless it's somehow failed.

Is the boiler piped inline with the system or is primary secondary?

Looks like your expansion tank is on the discharge of the pump which is bad. The expansion tank and makeup need to be on the suction side of the pump which will be the lowest pressure point in the system.

I'm assuming your inlet is the front port (and the pump is pumping downwards), and the outlet is at the back feeding into the air separator and expansion tank and makeup.




You are missing the valves to properly isolate and service the expansion tank. You need to be able to open the tank to atmosphere to set the pressure properly, this means valving off the system and having a drain between the pressure tank and isolation valve.

Also I don't like having air vents or system openings above things like the boiler, it's just asking for corrosion and a mess with small dribbles and leaks over time.

HomerJSmith

You are really pumping into your expansion tank, which is a no no. The expansion tank should be connected to the inlet to the pump at least 10 pipe diameters from the pump flange, as said.

I wouldn't replace the expansion tank unless it was water logged.
I have seen tanks that are still functioning after 15 yrs. What you really need to do if the tank has been in use for a long time is to recharge the tank with air to the system pressure, which based upon the Pressure Regulating Valve is about 15psi.

That Honeywell SuperVent air eliminator, (my favorite besides Caleffi), doesn't need replacing. Replacing all that would suggest, with out good reason, either your service person is ignorant or planning to retire and moving to the south of France with what he get on this job.

It's a good thing that you came to this site. The only motivation professionals here is to help others and to banish ignorance to the abyss of Hell. Choose your professionals carefully.

cnm

Is the boiler piped inline with the system or is primary secondary?

Looks like your expansion tank is on the discharge of the pump which is bad. The expansion tank and makeup need to be on the suction side of the pump which will be the lowest pressure point in the system.

I'm assuming your inlet is the front port (and the pump is pumping downwards), and the outlet is at the back feeding into the air separator and expansion tank and makeup.

I'm not sure about inline vs primary/secondary. How can I determine that?

You are correct that the pump is pumping downwards into the boiler on the return side. The hot water outlet is on the rear feeding into the eliminator.

I'm trying to make sense of the diagram you posted. I suspect I'm reading it incorrectly. Is the problem that I don't have a system circulator pump "pulling" out of the expansion tank? Or that there's no pipe bridging the outlet/inlet pipes (the max 12" separation in the diagram)?

Thanks everyone for the comments and advice, even if I'm not quite understanding everything.