How much boiler sealer to use?

Mathelo

I have an almost 30 year old Weil-McLain oil fired boiler that has started to leak when under pressure. Without pressure it seems stable but I'm sure it will get worse and I'll need to replace it. I'd like to buy some time and I'm going to try using the Hercules boiler sealer.

However, I'm unsure just how much I need and I've read the instructions multiple times. This is a 158000 BTU boiler originally driving baseboard heating on first/second floor and basement. It now drives hydro to an air handler on the second floor and one on the first floor. We've also added an indirect water heater. Basement still has the baseboard heating. Total heated square footage including the basement is about 3900 sq ft. If I'm reading the Hercules directions correctly, I should be using 1 qt for each 400 sq ft radiation. I'm interpreting that to mean 400 sq ft of heated space. So in my case, that would amount to almost 10 quarts of sealants for my system. That seems like a lot to me but I have no clue what the right amount is. I can't help wonder if their recommendation is based on baseboard heating as compared to hydro, which I expect has a lower volume of water.

What do you think? Does 2 gallons sound right?

Thanks!

Louis

pecmsg

Why not just replace the boiler. 

Mathelo

pecmsg said:

Why not just replace the boiler. 

I am planning to replace it but I hate being rushed. Just trying to buy some time. Even a couple of weeks. Right now the boiler is not heating but it is still providing hot water. We also have very efficient heat pumps that have held in there over the last couple of very cold days.

hot_rod

I've used this brand. I'd guess 2 pints or less, should cover your system. They have squirt cans also that thread onto a boiler drain or hose connection.

Mathelo

hot_rod said:

I've used this brand. I'd guess 2 pints or less, should cover your system. They have squirt cans also that thread onto a boiler drain or hose connection.

That sure is a lot smaller volume than the Hercules product but it does seem to have a somewhat different purpose. Its focus is on "microleaks". I wouldn't call this a microleak in a the system and it is in the boiler.

WMno57

I am not a fan of Bar's Leak in automotive radiators and Fix a Flat in tires. They make a mess and make future repairs more difficult. What will the boiler leak product do to your pipes and air handlers?
A 40 gallon electric resistance water heater is cheap. Get one of those for your domestic hot water.

Mathelo

WMno57 said:

I am not a fan of Bar's Leak in automotive radiators and Fix a Flat in tires. They make a mess and make future repairs more difficult. What will the boiler leak product do to your pipes and air handlers?
A 40 gallon electric resistance water heater is cheap. Get one of those for your domestic hot water.

I use tubeless tires on my bicycle with Stan's tire sealant so your reply doesn't resonate with me.

And there is no way I'm putting in electric resistance water heater, temporary or otherwise.

WMno57

How about a Heat Pump Water Heater? Several Wallies here have these and are all quite pleased with them. Your local electric utility may have rebates.

Mathelo

WMno57 said:

How about a Heat Pump Water Heater? Several Wallies here have these and are all quite pleased with them. Your local electric utility may have rebates.

Yes, I'm considering this but I still need to get my boiler to work a bit longer. No one has yet helped directly with my original question. Does 2 gallons of Hercules sealer sound right for my system?

Louis

Jamie Hall

The square feet almost certainly is the EDR powered by the system -- not the square footage of the building.

Use the smallest amount you can get away with. The stuff has a dismaying way of interpreting and small passage as a leak -- including the tubes in the air handler heat exchanger.

Also, if the leak in question has any significant size, it won't handle the pressure.

Mathelo

Jamie Hall said:

The square feet almost certainly is the EDR powered by the system -- not the square footage of the building.

Use the smallest amount you can get away with. The stuff has a dismaying way of interpreting and small passage as a leak -- including the tubes in the air handler heat exchanger.

Also, if the leak in question has any significant size, it won't handle the pressure.

Thank you for you reply. Apologies for the double post.

What does EDR mean?

Mad Dog_2

I've never heard of that brand HR.  I'd like to try it.  You get it online? Thanks mad dog

Jamie Hall

EDR is a measure of the effective area of the radiation in the system. Your boiler is probably well oversize, but it will have the capacity to power about 500 square feet equivalent of radiation.

Mathelo

Jamie Hall said:

EDR is a measure of the effective area of the radiation in the system. Your boiler is probably well oversize, but it will have the capacity to power about 500 square feet equivalent of radiation.

Yes, it is oversized. I recently did a manual J calc and including the basement but not the water heater it came in at about 90000 BTU. I’ve read that indirect water heaters should add 25000 so that gets me to a generous 115000 particularly since I don’t really heat the basement.

In any case, the Hercules directions call for 1 quart per 400 sq ft radiation, which is quite a bit less than 2 gallons.

hot_rod

There is no way you need two gallons, that would gum up your pumps and most every passage way.

I would think the two products are similar and the mix ratio also.

Fernox is a UK brand, used for steel and cast iron products, radiators or boilers.

The ability to seal depends on the size of the hole of crack.

8- 10 psi would be my suggestion.

Mathelo

hot_rod 8- 10 psi would be my suggestion.

What do you mean by this?

hot_rod

Mathelo said:

hot_rod 8- 10 psi would be my suggestion.

What do you mean by this?

The pressure that you operate the boiler at. Keep it as low as possible. The air handler on the second floor is the highest point in the system?
How high above the boiler is it? You need enough static (fill) pressure to get the water up to the high point

Distance from boiler to high point X .433 psi.

.433 psi lifts water up 1 foot.

Make the math simple, 1/2 psi per foot. So if the high point is 16' above the boiler you need 8 psi.

Mathelo

That’s helpful. Probably closer to 24 ft so 12 pounds of pressure. The oil company technician was shooting for 20 so I’m going to target the lower pressure.

WMno57

Is the goal of this project domestic hot water or DHW and heat from the air handlers. If the former, you could valve off or cut the lines to the air handlers. SharkBites and oxygen barrier pex can make life easier.

Mathelo

WMno57 said:

Is the goal of this project domestic hot water or DHW and heat from the air handlers. If the former, you could valve off or cut the lines to the air handlers. SharkBites and oxygen barrier pex can make life easier.

Until I replace the boiler, it is just for DHW. My heat pumps are providing sufficient heat. What would I gain by cutting off the lines to the air handlers?

WMno57

Not plugging up perfectly good working air handlers with Hercules Boiler Sealer.

Mathelo

WMno57 said:

Not plugging up perfectly good working air handlers with Hercules Boiler Sealer.

Got it. Can't I just shut off and turn off the circulator pumps to achieve the same thing?

WMno57

Maybe. Depends on how everything is connected.

Mathelo

WMno57 said:

Maybe. Depends on how everything is connected.

In the attached image you can see the circulator pumps that feed the hydro in the air handlers. I can isolate these

Mathelo

After talking to my local support, I now understand that isolating the circulator pumps does nothing. This is just on the return.

todd_14

I have used Hercules boiler sealant in an older 1980’s oil fired hot water system. 

I added the 1 qt bottle to a few gallons of water in a bucket and mixed it. 

I turned off auto fill and relieved pressure in system.  I then placed a sump pump in a  bucket and connected a short hose to a drain bib/silcock on the system.  I turned on the pump-& opened the bib.  It then pumped right into to system. I closed bib, added another gallon of water and re-peated. 

Afterwards I turned auto feeder back on. 

Sealer worked well to seal a weeping, heavy corrugated, packed rusted pipe that was actively leaking water thru the pack rust. 

hot_rod

If a pint, maybe two doesn't stop the leak, it is beyond what a sealer can take care of. No need wasting more sealer money after two doses.

I doubt a pint, even two will plug up pumps, it stays liquid, in suspension until it sees a source of O2.

Automotive cooling systems plugged from folks continuing to add the leak stop, instead of knowing when to admitting defeat

Locktite, it stays liquid on the outside of the thread, hardens in the absence of O2, anaerobic, the opposite of boiler sealers.

Mathelo

I got a quart of the sealer into the boiler. I isolated all zones except the DHW. I am leaving those zones closed for now since I'm not using them at this time. If by chance we see subzero temps before I swap out the boiler, I'll be temped to open them up but we should be clear for the next couple of weeks (our average January low temps are in the teens). I pumped back in about half of the water I took out to 10lbs of pressure and fired it up. I still see some steam coming from the leak area but the boiler has now held the pressure for at least an hour. I'm taking that as a very positive sign.

EBEBRATT-Ed

@Mathelo

Simply look on the boiler name plate, It should give you the boiler output in "square feet of water" where it shows the heating capacity. Then you will know the maximum amount.


You want to use the minimum amount to slow or stop the leak. Start with 1/2 the amount

Mathelo

EBEBRATT-Ed said:

@Mathelo

Simply look on the boiler name plate, It should give you the boiler output in "square feet of water" where it shows the heating capacity. Then you will know the maximum amount.

I don't see that on the label.

MikeAmann

Mathelo said:

I got a quart of the sealer into the boiler. I isolated all zones except the DHW. I am leaving those zones closed for now since I'm not using them at this time. If by chance we see subzero temps before I swap out the boiler, I'll be temped to open them up but we should be clear for the next couple of weeks (our average January low temps are in the teens). I pumped back in about half of the water I took out to 10lbs of pressure and fired it up. I still see some steam coming from the leak area but the boiler has now held the pressure for at least an hour. I'm taking that as a very positive sign.

1 quart is all you need, you did that and it seems to be working. Don't mess with it any further.
It's either going to hold, or it isn't. I think you will be fine.

EBEBRATT-Ed

@Mathelo

158000 btu/150=1053 sq feet of hot water radiation

Mathelo

EBEBRATT-Ed said:

@Mathelo

158000 btu/150=1053 sq feet of hot water radiation

Where does that 150 come from?

Based on this calculation I could add another quart but I won't at this time. No leak currently. And again, all zones are off except for the DHW.