Boiler/Floor Heat

[Noob]

I took over a wash that was roughly 20 years old. The wash originally plumbed for floor heat but the boiler and all equipment were pulled out when I took over the site. I have no idea when the last time floor heat was even used. I’m looking into possibly getting a boiler but have a couple questions.

I know I need to pressure test the lines before I do anything.My question is at what pressure should I test them. The lines are not pex. I believe they are black rubber? Anybody have any idea what the life span for those lines might be?

Assuming the lines are fine (which is a lot to asssume) would I need to clean the lines out somehow? Possibly by hooking up a water hose to one end and flushing everything out?

Lastly I’m trying to get a rough estimate for a boiler size. I have a 4 bay located in East TN.

 

[mjwalsh]

I took over a wash that was roughly 20 years old. The wash originally plumbed for floor heat but the boiler and all equipment were pulled out when I took over the site. I have no idea when the last time floor heat was even used. I’m looking into possibly getting a boiler but have a couple questions.

I know I need to pressure test the lines before I do anything.My question is at what pressure should I test them. The lines are not pex. I believe they are black rubber? Anybody have any idea what the life span for those lines might be?

Assuming the lines are fine (which is a lot to asssume) would I need to clean the lines out somehow? Possibly by hooking up a water hose to one end and flushing everything out?

Lastly I’m trying to get a rough estimate for a boiler size. I have a 4 bay located in East TN.

Noob,

I would not pressure them up to air test much more than your maximum boiler pressure. Our system's inline gauge actually has been left at less than 1 psi & the way the pump is set up that has not been a problem with enough flow. This might not apply to your system.

When expanded (2001) our original deicer (1980) with what the local HVAC contractor & supplier recommended at the time. It was a special RUBBER hose that had wire reinforcement within it. It was manufactured specifically for floor heat. That was about 19 years ago ... hopefully it will not give us grief. I did see that the company was sued for failures & maybe is no longer in business ... not sure.

I would flush them out if it was mine because you can also start from scratch (clean no particles) etc. ... adjusting the pH glycol level also etc.

I am pretty sure that most car wash distributors & possibly on the Raypak website they have a map of design requirements. We are in the minus 30° F design area on the map in our north dakota location! With the design they show the recommended BTUs of the boiler.

Too bad you weren't closer freightwise ... it could makes sense for you to pickup our 399btu TP Raypak (lowball offer ... a properly sized pump for your system would be needed) that most likely has many years of trouble free use left in it considering we bypassed it & routed the deicer to our laundromat's 3 boiler that has 3 stage modulating ability. Our specific deicer system mainly only runs during colder evening-morning hours with the controls prioritizing for the laundromat domestic. Like JGuinter on a current thread observed ... the slab keeps its heat for longer than we might think.

 

[2Biz]

I have the same black plastic hose for floor heat. I don't think they made pex when this was installed. FWIW, I upgraded the old 350k Jarco with a 199k demand heater and couldn't be any happier.

To answer your question on pressure check. I run my system at 10 psi filled. I would fill it with water, purge all air, and let it sit for a week to monitor. All other questions about using a demand heater instead of expensive boiler can be found here.

Tankless Water Heater For Floor Heat

Anybody care to share information about using the new style tankless water heaters for floor heat? I need to replace my old Jarco 350K btu money pit with something new and more energy efficient. I’ve been doing some extensive research and comparing different demand heaters, Takagi, Paloma...

www.carwashforum.com

I think you can source a Takagi 199kbtu for under $1000. It will be perfect for a 4 bay. Mine is on year 7 and not a single issue!

 

[mjwalsh]

Noob,

2Biz has some previous thorough posts that also show a nifty way to keep the pump cost down that could apply to yours depending on your specific elevations & the square footages etc.

 

[Noob]

2biz, I’ve looked through that thread numerous times. Someone told me that a tankless heater was not permitted for space heat/floor heat and therefor would not be up to code?
I’m all for the most economical solution. I would probably have to get some professional help for the installation. I don’t have an previous experience installing water heaters or boilers. I’ll ask one of my local plumbers if it would meet code to do so.
My original plan was to test the lines with compressed air. Would liquid be better? How old are the lines in your floor system?

 

[2Biz]

I'm guessing close to 40 years old on the tubing since the manufacture date of the old boiler was early 1980's.

As for code, you might find anything under 200kbtu falls under certain guidelines not requiring a certified boiler technician to do the install or maintain it. That's why a lot of these demands are 199kbtu!

There are a lot of old myths about using demand heaters for floor heat. But if you do your research, there are a lot of retailers/installers that are going against the myths compared to 8-10 years ago! I'm one of them. Mine has been installed since 2012 and not a single issue. If the heater ever did go belly up, it wouldn't take an hour to swap it out. And for less than a grand, it would be cheaper to replace than hiring a certified tech to do the work.

 

[2Biz]

As for testing lines, I originally tested mine using water and pressurizing to 10 psi.

 

[JGinther]

Heating anything other than domestic water falls under an asme stamp requirement. If the heater is asme rated for hydronic heating, it would be allowed... from what I understand anyway.

 

[mjwalsh]

As for testing lines, I originally tested mine using water and pressurizing to 10 psi.

I could be wrong ... but it seems like air would more likely show a problem in the tubing or fittings etc. Ours were tested with air.

We used silver solder on the 2" type K copper portion that Huron Valley's blueprint recommended. I had to go back & redo some of my brother-in-law's silver soldering with the Acetylene torch that he left with me for awhile. I was told later that the silver solder that I chose was the strongest but not the easier to work with. BTW ... the copper was wrapped in thin plastic as a precaution against chemical attack on the portion that was copper.

Since the original portion of deicer was done in 1980 ... we did notice that the cross-linked version of black polyethylene tubing .... maybe before they called it Pex??? ... did eventually get a bit brittle where ever it was in contact with air ... such as in our two manifold boxes. There it is more repairable ... not needing to break an area of concrete up ... yikes!

 

[Noob]

2Biz, I’ve been reading and rereading your thread about using a tankless heater. My wash abs your wash seem to be very similar. I figure I have about 1500 square feet to heat plus I’d like to heat the trough. My lines are 1/2” going out to the bays.
I believe I’ve got a good handle on the primary secondary plumbing. What I don’t understand is calculating head pressure. I’m trying to determine what pumps would be optimal. One site said to divide your pressure by 2.31 to get PSI. Is that correct? Does the length of my primary and secondary loops factor in to the equation?

 

[2Biz]

Is your ER right in the middle of your 4 bays? That would be the best scenario. Mine is offset with 3 bays to the left and 1 to the right. It hardly makes any difference though, you just have to make sure the loops get the right flow so the return loop temps are about the same. You do this with ball valves or any kind of mechanical flow control valves for each loop. Once set, should never change. Mine hasn't anyway...

Since your wash is exactly the same foot print as mine, I would think you can use the same pump configuration as I came up with. A single Taco 013 on the secondary bay and trough loops (5 Loops). And (2) Taco 0013's in series for the Primary loop in order to give the demand heater enough pressure to get max flow through it. (2) 013's in series gives 40psi pressure to the heater at 6.7 gpm flow...If you read the flow charts on the heater, it takes 100 psi to get the full 10gpm, but the delta T would have to be minimal to get this flow.

Somewhere I read you only want about 2-3 gpm flow through each zone to maximize heat transfer. With 5 loops, this is only 10-15 gpm total....When I did my calculations, the 0013 for the secondary loops was more than adequate to give the necessary flow while maximizing cost savings on electric usage. It runs on only 2a of 120v....

You are correct you divide head pressure by 2.31 to get PSI....The Taco 0013 has a max head of 33 or 14.28 psi. I believe I calculated 28ft of head pressure of my longest loop. According to the Taco's submittal sheet, the 0013 puts out 10gpm at 28ft of head which is right in the 2 gpm flow per loop I needed. And yes, loop length affects head pressure. You have to do the calculations to make sure you are within the range of the pump.

 

[2Biz]

Here is how I have my zone flow valves set. The one to the left is my truck bay, 3 bays from the ER 100% open. Then Bay 2, 2 bays over from the ER. Bay 3 and 4 are the same since they are on either side of the ER, restricted more compared to bays 1 and 2. The 5th zone is my trough heat. I have it opened up all the way since there is very little heat loss in this loop. It works great!

 

[Sequoia]

When I bought my wash it had a Weben Jarco 350,000 btu floor heat boiler. And a thermostat. So at 35 degrees outside air temperature, it fired up and went full blast until the outside air temperature warmed back up-- usually 12 or 14 hours later. It was inefficient in multiple ways-- it cost a fortune to operate and it kept the equipment room as a shirt sleeve environment from all of the losses. The propane company loved me.

I replaced it with a Lochinvar 150k btu boiler from Car Wash Boilers. What a dream come true. When the temp gets down to 35 degrees, it fires up at full blast to get hot water circulating. But, there is an important difference. It has a return water sensor that evaluates the temperature of the water coming back to the boiler after running through the slabs.

My return water sensor is set for a 70 degree cutout. So as the Lochinvar senses return water in excess of 70 degrees, it modulates the flame down. So it is smart enough that if it doesn't need to operate at 150k btu, it reduces itself to something less.

Here is what I learned: a) the Lochinvar will modulate down to 20% of maximum btu. So in my case, it can become a 30k btu boiler. b) On most nights I have visited, once the slabs have been warmed by the circulating water, the boiler is operating all night at 30k btu. After installation, I was burning about 10% of the propane compared to the Weben Jarco unit.

I'm not in a terribly cold climate so the ability to modulate the flame down works very well for me. If it got really cold it would be less of a savings, but I'd think the ability for whatever unit you choose to modulate the flame down would be a worthwhile investment.

 

[mjwalsh]

Sequoia, 2Biz, Noob, & others,

Another thing that was not mentioned with Noob's project ... the needed density of the glycol also affects the BTU transfer. There are charts on the internet that shows the variation. So that would be another variable involved. You referred to your circulating fluid as "just water"?

I hope the horrific fires are not too close to you. We are still getting hazy skies on otherwise clear days. When I was in Guatemala ... in a unfamiliar similar fires made it so it was not possible for me to know north south east west because of the dense haze. I see a bunch of firefighters are coming from other states to help out including from here in North Dakota.

 

[Sequoia]

Good point about the glycol. The addition of that does make the transfer of heat to the slabs more efficient.

When my system was installed, my plumber carefully evacuated all of whatever fluid was in the lines previously. That fluid had been in there for decades. I don't remember the water/glycol ratio that was added to replace it, but I do know there was some of each.

 

[tdlconceptsllc]

Heating anything other than domestic water falls under an asme stamp requirement. If the heater is asme rated for hydronic heating, it would be allowed... from what I understand anyway.

I understand in my state bc I got in trouble for not having a ASME stamp it's anything over 199,000btus and 120 Gallons you are required to have a ASME stamp welded on the tank. I bought a used 299,000 heater but did not have a ASME stamp and had to remove it went with a tankless and bypassed all those rules

 

[mjwalsh]

https://aeroventic.com/attachment/download/1421

As a caveat ... a trustworthy HVAC Engineer may be needed to interpret the above pdf. Most of us far enough north or in high elevations know that there is a danger of tubing or whatever bursting from expansion if we don't have the proper ratio of water to glycol. Sizing & efficiency is affected & should not be taken too lightly IMHO!

 

[Noob]

My ER is in the middle of the bays. I was honestly hoping I could copy your setup biz. If I remember correctly the Takagi has to have a minimum of 40psi to operate. How do
you get 40psi when the pumps are only putting out 14-15 each?
My understanding is that the primary loop is operating at a higher PSI than the secondary loop?
Can someone explain to me the differences between a boiler and a tankless heater? They seem to be very similar but boilers are 3-4x the price? Are boilers plumbed with the same primary secondary loop system or are they plumbed directly into manifold?

Sequoia, what part of the country are you in? Do you have any idea what the utility cost is to operate your boiler? $100 a month? Less than that?

Definitely learning a lot. Thanks to all you guys for sharing your knowledge.

 

[mjwalsh]

Noob,

It seems like the key difference is that boilers have more internal fluid internally which probably helps them once filled to keep up the heating ability longer. Some difference in controls might also be helpful though to accommodate the less or no internal fluid in the tankless!

Both can be set up in modular ways so if only one is needed among multiple units ... it can save on fuel ... most of us are on the usually more reasonably priced natural gas.

I notice by 2Biz's pics ... he is using a similar air eliminator that we added during our last fall's hydronic update.

 

[Noob]

Are you guys using closed systems? One other things that confused me is I have soon some drawing that are labeled closed system but that have feed water plumbed into them? Wouldn’t that make them an open system? If your using a water glycol mixture you wouldn’t want feed water would you?