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Another tankless water heater replacing boiler thread

OurTown

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I did some research on boiler code in Ohio. They do require any pressurized commercial hydronic heating system to have a state inspection and have an ASME certified boiler. Just to clarify I called a state inspector and he said that is all correct. The under 200K BTU rule is only for domestic hot water. According to the inspector the installer only needs to register with the state and pull a permit for the initial inspection before firing. I can't find any tankless water heaters that are ASME certified. They are all boilers and some boilers are not even ASME certified.
 
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On boiler size I don't think we need all that big of one. Our old one is an 82% efficient 627K BTU running on about halfway on the gas valve setting. If that is truly set for only half the output (I need to verify this) then we are talking only about 257K BTU output. Factor in only needing about 85% of that for having several less tubing runs and then we are down to 219K BTU. That would only be about a 230K input boiler if 95% efficient. The new runs will be much easier to heat than the old self serve side which is under all that concrete and not insulated. We can probably throttle back the new runs just a tad and save a tiny bit more on boiler size.
 
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OurTown said:
I did some research on boiler code in Ohio. They do require any pressurized commercial hydronic heating system to have a state inspection and have an ASME certified boiler. Just to clarify I called a state inspector and he said that is all correct. The under 200K BTU rule is only for domestic hot water. According to the inspector the installer only needs to register with the state and pull a permit for the initial inspection before firing. I can't find any tankless water heaters that are ASME certified. They are all boilers and some boilers are not even ASME certified.
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Our Town…I am also in Ohio. Here is what we did and what I suggest you do. We have several washes with Raypack floor heat systems designed by Huron Valley. Our one air-x tank rotted out so I replaced it with an open top square plastic tank with a lid. When the inspector came back the next year he looked at it, noticed the lid simply lifted off and he said we no longer needed to have it inspected as it was open air. There is no way it can build pressure. So at our other locations I simply removed the plug on the top of the air-x tank and replaced it with two street elbows together making an upside down J so nothing can fall in the tank. No more inspections. If you happen to put the plug back in after the guy leaves I’ll never say a word.

I should have mentioned all those Raypacks are over 500k+ btu’s.
 
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GoBuckeyes said:
Our Town…I am also in Ohio. Here is what we did and what I suggest you do. We have several washes with Raypack floor heat systems designed by Huron Valley. Our one air-x tank rotted out so I replaced it with an open top square plastic tank with a lid. When the inspector came back the next year he looked at it, noticed the lid simply lifted off and he said we no longer needed to have it inspected as it was open air. There is no way it can build pressure. So at our other locations I simply removed the plug on the top of the air-x tank and replaced it with two street elbows together making an upside down J so nothing can fall in the tank. No more inspections. If you happen to put the plug back in after the guy leaves I’ll never say a word.

I should have mentioned all those Raypacks are over 500k+ btu’s.
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We are currently not pressurized on our Raypak and do not get yearly inspections on that boiler. My late friend was a HVAC guru and told me that it was more efficient to run pressurized. The only disadvantage to run non pressurized that I see is the yearly inspection. I was hoping to run a loop into the new attic trough and if not pressurized I don't think it will push. I could maybe put in an auxiliary pump just for that loop or run electric heat wire though.
 
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After doing some digging I found that the adjustment knob on the gas valve is called a "modulation knob" and is for system temperature set point. There are two different sets of temps in the manual. At set point "4" is 137F for low temp DHW but "4" is 177F for high temp hydronic heating. How does the boiler know what it is being used for?
 
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After looking at hydronic floor heating systems online they all seem so much more complex than what we have currently. More pumps and solenoid valves plus other things. Ours has only one pump for the whole system. Also when looking at non pressurized systems they all seem to be open systems connected to water sources. Obviously we don't want that for a de-icing/snow melt system. When referencing closed loop they all are pressurized to 15 psi and most run propylene glycol. They claim that pressure is required to prevent heat loss and oxygen to enter the system causing corrosion to heat exchanger or pumps if cast iron. Our system is using ethylene glycol and from what I have read is superior for heat transfer but of course is toxic to animals. Would this prevent corrosion if oxygen is present? How much less efficient is a non pressurized system? If going from non pressurized all these years to pressurized what are the chances we will spring a leak in the old tubing runs? After all this I'm starting to wonder if we should just keep our 21 year old boiler and of course leave it non pressurized. It will probably short cycle more now, we will have to cut a big 14" hole in our beautiful new roof and ER ceiling, takes up a lot of space and won't be as efficient as a new one but it works!
 
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You are asking some really good questions, sorry I don't have answers to all them...But can tell you, my Takagi heater is about 10-11 years old now....It was origianlly pressurized to 10psi....I haven't touched it or added anything to it in 10 years running the same old black plastic water tubing that was installed 50 years ago. ALTHOUGH! Pressure does drop to zero when the heater is off and the main circulator is running....When the heater turns on, pressure comes back up to 10 psi! So is this an issue?! I don't think so becasue it always works the way its supposed to. My motto, is if it ain't broke don't fix it. Just keep a closer eye on it! I used Propylene glycol at about 30%. Gives me freeze down to zero and burst to -50°. Way more than enough. I also used distilled water to eliminate the oxygen issue. I don't think if I was putting in all that time and $$$ to your remodel/upgrade, I would not want to keep a 21 yo boiler....A new HE one will pay for itself in no time!
 
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2Biz said:
You are asking some really good questions, sorry I don't have answers to all them...But can tell you, my Takagi heater is about 10-11 years old now....It was origianlly pressurized to 10psi....I haven't touched it or added anything to it in 10 years running the same old black plastic water tubing that was installed 50 years ago. ALTHOUGH! Pressure does drop to zero when the heater is off and the main circulator is running....When the heater turns on, pressure comes back up to 10 psi! So is this an issue?! I don't think so becasue it always works the way its supposed to. My motto, is if it ain't broke don't fix it. Just keep a closer eye on it! I used Propylene glycol at about 30%. Gives me freeze down to zero and burst to -50°. Way more than enough. I also used distilled water to eliminate the oxygen issue. I don't think if I was putting in all that time and $$$ to your remodel/upgrade, I would not want to keep a 21 yo boiler....A new HE one will pay for itself in no time!
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If the pressure drops to zero when off then would that be a non pressurized system? Maybe there is corrosion protection in the alcohol to prevent rust on the cast iron pumps. I really want to replace this boiler and this is the time to do it with being shut down for a big remodel.
 
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OurTown said:
If the pressure drops to zero when off then would that be a non pressurized system? Maybe there is corrosion protection in the alcohol to prevent rust on the cast iron pumps. I really want to replace this boiler and this is the time to do it with being shut down for a big remodel.
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I was thinking the same thing! Could you pass this off as a non pressurized system?? I think not since it is closed....LOL...I used NoBurst that is supposed to have rust inhibitors in it...So far I haven't had any issues...
 
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2Biz said:
I was thinking the same thing! Could you pass this off as a non pressurized system?? I think not since it is closed....LOL...I used NoBurst that is supposed to have rust inhibitors in it...So far I haven't had any issues...
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A pressurized system keeps its pressure when off and cold. (I did more research) Where are you measuring pressure?
 
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2Biz said:
I was thinking the same thing! Could you pass this off as a non pressurized system?? I think not since it is closed....LOL...I used NoBurst that is supposed to have rust inhibitors in it...So far I haven't had any issues...
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I looked at your video again and saw five gauges but you only showed two of them. I'm not sure which ones of the other three are temp and which ones are pressure.
 
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Its just before the main circulator...Of the two gages shown, its the one on the right....This picture was taken when I fist started up the system. I had it set to 20psi...Later, changed it to 10psi.

 
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What did you change to make it go from 20 psi to 10? Is there a regulator or did you open up a ball valve more? IIRC if the system runs sub 15 psi it is not considered pressurized.
 
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Overachiever said:
I'll try and take some photos when I'm over there tomorrow, it's definitely not pretty, but I used the taco pumps that 2Biz used.. 2 in series going up toward the takagis and another right before the manifolds to the bays. I have another small one on the pipe that goes up toward the roof trough. I tried my best to do the primary secondary configuration 2Biz spoke of in his post where some of the output from the takagi's mixes back in with the cold coming back to increase efficiency.

I didn't install a thermostat, lol, I don't think my old slab stat was working. I've got mine plugged into smart switches right now and just manually turn them on and off if I feel like saving more money, but 2Biz (or someone) told me I should use the weepmizer, which seems a lot more smart.
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Did you ever take any photos of your setup?
 
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OurTown said:
What did you change to make it go from 20 psi to 10? Is there a regulator or did you open up a ball valve more? IIRC if the system runs sub 15 psi it is not considered pressurized.
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No regulator...I just let some glycol out from the service valve!
 
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2Biz said:
No regulator...I just let some glycol out from the service valve!
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What makes your system lose all pressure when it shuts down and a normal boiler system keep its pressure?
 
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No Clue....Even though the main cicrculator is pumping, when the heater turns off, the pressure drops to zero. When the heater turns on, pressure comes up to 10psi...Maybe expanding glycol as its heated?? Bout all I can think of? Maybe I need to check the pressure on my expansion tank? Been this way for years!
 
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I don't think that is technically a pressurized system.
 
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My thoughts are that they consider a closed loop system a pressurized system whether you have it pressurized or not. The point is that it could build pressure and if it did you're relying on the psi relief to relieve that pressure to prevent an accident, hence the required inspections.

A long time ago I asked Huron Valley why there was an air valve on their Air-X tank. They told me it was to be able to add a little pressure which would help if you had harmonic noise in the system but otherwise not to use it. They never mentioned anything regarding it making the system more efficient?
 
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