I could use help replacing expansion tank in glycol boiler. Pic included.

clydesdale

Hi. I could use some help, as my boiler guy is backed up and has no idea when he can get to me. My pressure relief valve has been leaking and I have had to empty a 5 gallon pail a few times. I did not think this through and thought this was just a minor headache. But, I believe I diluted most of my glycol. I have a air handler in an unheated space and last night it got down to 9 degrees. The system was not heating well at first, but it then started working, after an hour and a half. I am not sure if the coil was partially frozen or if there was an air pocket. At one point I had to turn the heat on down stairs in order to get the boiler to turn on and heat the water for upstairs. I then kept the heat at 62, so it would keep turning on. I heat mostly with wood and upstairs will get to upper 50s during the night.
So, I have an expansion tank coming today. My current one is filled with water. I hit the schrader valve and some water came out, certainly not air. I want to replace that at least and see if I can stop that issue and then keep the heat on til the guy can get here. Do I just shut the ball valve on either side of the tank, unscrew it and then replace it? One valve is right below the tank and one is near the water tank. The water flows to the left in the picture. I have a 4.4 gallon 12psi tank coming today. Thanks!!

Intplm.

Can't see the shut-offs that you are describing? Some pictures further back should help, as well as a picture showing where the expansion tank is connected.

clydesdale

I put a glove on one of the shut offs because it is in line with the pipe and facing the camera, so hard to see. I believe I shut the glove off and the ball valve that is on the left side of the tank. Then simply unscrew the tank, tape the threads, screw the new tank on and open the valves. But I could be wrong. Thanks.

hot_rod

I do not see a valve right under the tank, so you need to drain down, relieve the system pressure.

That tank will be 35 lbs or more if it is waterlogged, be ready for that.

Did that tank work in the past? you sometimes need to upsize tanks a bit when you use glycol. What does the pressure rise to when the boiler hits high temperature?

Install a 1/2" valve under the tank for future replacements. A valve like this allows you to isolate the tank and take pressure off through the side port.

clydesdale

Isn't that valve below the tank and to the left the one I shut off and the glove one? This way I shut off water coming into and passed the tank?

clydesdale

Yes, the tank worked in the past.

hot_rod

I may not be a good idea to have a fresh water fill system connected to a boiler that has glycol. As you discovered thje water will dilute your glycol and render it useless. Most glycoled systems include a small fill tank like this with a 4 or so gallon of glycol reserve. A small pump inside maintains the boiler pressure.

A low water cutoff on the boiler protects it from firing should all the water drain out.

clydesdale

That is an interesting device and I will look into that. Can I change this expansion tank the way I described to at least stop the leak and then get a pro over here to charge the glycol when they can?

hot_rod

If you shut off the fill valve that puts water into the system, and the relief valve pops off, a portion of the water in your system will be drained out, depending on how long the valve discharges. You will probably end up with air locks and the inability of the pump to circulate any flow, since no water is able to replace what just discharged out of the relief.

If the tank is completely waterlogged you have no expansion space for the heated water to expand into.

You want around 10- 12 psi in the boiler to lift the water to the highest point in the system. Maybe that is the air handler mounted above the boiler somewhere?

Since the glycol is diluted, may as well drain the entire system, if you want to pump in a glycol solution again?

Buy buckets of a 30% pre-mix to eliminate the need to calculate system volume and blend glycol on site. You will need a pump to get the glycol from the bucket into the system also.

HomerJSmith

An Ex tank should not be installed upside down. Air gets trapped in the water side of the diaphragm. By all means install the valve that hot_rod suggests you use. It makes changing a tank so easy as you don't have to drain down the sys, also it makes it so easy to air charge the tank to 15 PSI if needed.

EBEBRATT-Ed

@clydesdale

Shut the boiler off. Close the two valves you mentioned on either side of the tank. Have a bucket handy.

Drill a hole in the expansion tank with a 3/8 drill bit. Use a cordless drill. The metal is pretty thin so it will go fast. Be ready for water because your going to get some. Drill the hole in a place where the water won't hurt anything and catch it in a bucket. Make sure the tank is cool or warm when you do this.

Replace the tank with a valve as @hot rod mentioned.

It would be better to have your service tech relocate the tank, (threaded nipple up) when he comes

hot_rod

If you get a glycol tester you could check the glycol %. If there is still some protection you could buy a stronger mix and maybe not drain the entire system.

Are you wanting to run the glycol solution again?

I've known contractors that use freeze stats that fire up the pump to keep water moving during a low temperature condition at the AH.

But power outages can throw a wrench in the works with that method.

pecmsg

and install one of these

https://www.supplyhouse.com/Webstone-H-44672-1-2-Pro-Pal-Full-Port-Brass-Ball-Valve-w-Hi-Flow-Hose-Drain-FIP-x-FIP-600-WOG

clydesdale

OK. I had a boiler repair friend come over and assist me with replacing the tank and the PRV. I walked him through what I planned to do on the phone the night before and he insisted on helping me out, which I greatly appreciated. I am totally capable of this repair. We shut off all the zones, shut power to the boiler, turned both valves in the picture, relieved the pressure by lifting the pressure relief valve and then unthreaded the full of water expansion tank. We then threaded on a new tank and new PRV. It heats fine. Thank you. Now the question is what to do about all the glycol that I diluted. There is literally none left. I am going to make a new thread about that later tonight. Thank you so much guys!!!!

EBEBRATT-Ed

@clydesdale if there is some glycol left you could test it and then calculate how much to ad but for a small job that is not worthwhile.

I assume you have polypropylene glycol so it can be dumped down the drain and diluted. So I would dump the system. Refill it dup and refill and dump. Then since you usually don't know the system volume mix the glycol with water 30% glycol to water is usually enough and pump it in until the system is full.

Some like using distilled water or inhibitors or use a flush cart. Others will comment.

mattmia2

i was going to suggest you might want to try a compressor or tire pump and see if you can pump the tank back up and if there is water on the air side or not, it might have just lost its charge without the bladder being bad, it tends to leak out over a couple years, but it is too late for that now.

clydesdale

The expansion tank was full of water. Nearly 5 gallons of water came out of it. Thanks.

The % of glycol mix is definitely one thing that I am curious about because the stuff seems expensive.

mattmia2

if there is no air on the air side it will fill with water. unless the water is on the air side it isn't bad.