Tankless Water Heater For Floor Heat

[2Biz]

Something else I might add...I included (5) service ports/valves in the piping...You need them all! Don't skimp.... It would be very difficult to purge the air out of the system or drain it without the service ports. This is something my old system didn't have. It only had one fill valve and an open capped copper tube. There was no way to pressurize and purge air out of the system...

Another thing, designing a closed system has its benefits...You can use the cheaper cast iron circulators because oxygen can not get into the system which causes rusting and corrosion. Open systems need either bronze or stainless steel pump housings to control corrosion from oxygen which add to the cost.

There are additional benefits to having a closed system. When you pressurize the system it helps the pumps keep the fluid moving, easier. It has to do with the negative pressure the pump creates behind the pump. Pressurizing the system helps balance out this negative pressure. Where I work, the "Boiler Guy" told me some of their huge circulators won't pump anything at all unless the system is pressurized. So...Its something to consider....

Jeff

 

[Bubbles Galore]

If it wasn't for the fact I bought undersized pumps to start with, I would have had about $3500.00 in it. When you do your calculations, study the flow chart graghs of the boiler/demand heater and also of the pumps and make sure you order the right size. There is also an allowance that needs figured depending on the percentage of glycol your using in the system. It in itself adds head pressure. I used Noburst mixed @ 35% which will get me freeze protection down to 0°, flow protection down to -10°, and burst protection down to -60°....The glycol alone was $350.00....Expensive stuff....

If you factor in that I got $310.00 for the copper that was in the old boiler, the complete system cost about $3200.00...

Please keep the updates coming as we move into winter as I will need to heat about 4000 sq. ft. and want to see how well this works out for you through this winter. You've impressed the hell out of me so far and hope this works well for you.

John

 

[GoBuckeyes]

Okay, so I'm looking for information on tankless heaters to replace a leaking hot water tank on one of my autos and an hour later, here I am fascinated by this thread. This is something I have wanted to do for a while but could never seem to get enough information. Thanks for taking all the time to help others out 2Biz.

One question I have is why the 20 degree differential on your aquastat?

All my floorheat systems are old Raypacks designed by Huron Valley with their air-x tank and giant Taco pumps. Has anyone successfully eliminated their Raypack with a tankless?

 

[2Biz]

One question I have is why the 20 degree differential on your aquastat?

All my floorheat systems are old Raypacks designed by Huron Valley with their air-x tank and giant Taco pumps. Has anyone successfully eliminated their Raypack with a tankless?

I chose an Aquastat that had adjustable differential. From 0-30°...So I set the return line temp at 80° with a 20° differential. My initial settings might not be what I stick with, it just hasn't got cold enough to run it for more than testing. With a 20° temperature differential, I'm hoping the range is far enough apart so the heater doesn't short cycle. So basically when the return temps hit 60° the Boiler pumps kick on untill they reach 80° again completing the cycle...Again, both those settings might need adjusted when it gets cold enough to test the real thing. My original tests were performed when it was about 40° outside. It didn't take the Takagi long at all to get return temps to 80° to shut the pumps down.. The zone circulator keeps running till the outside air temp rises above 33°...

My old dinosaur, a 350K BTU Jarco was rated at 70% efficency 25 years ago. When I tore it out and took it apart, all the copper fins on the coils had corroded and was gone. This was from previous owners running it at a "Condensing" temperature which basically ruined it. I'm assuming the efficiency was down around 40% or even lower....

Continued next post...

 

[2Biz]

Doing the math, 350k BTU at 70% efficiency is roughly 245K btu rated output. So the Takagi I bought is 199K BTU at 95% efficiency which is very close to the capacity of the old Jarco when new. I'm only off about 50K btu but well within the calculations for my area on BTU per square foot. (125 btu per square foot).

So to answer the second part of your question, why wouldn't a demand heater work in place of the Raypacks? It should. I replaced the old Jarco and mentioned the reasoning above..I've also overcome the "Head" issues that most of these demand heaters have and at a very low cost to operate...4 amps of 110v for the boiler pumps...You can also put these units in series if you need more output than (1) 199K BTU has...Another plus is boiler inspections. Anything under 200K btu and you don't need inspections!

There is a lot of new information on line that we didn't have years ago when these old systems were installed. The only way I'm able to make any $$$ at owning this wash is to make it as economical to operate as possible. Hope this helps!

 

[mjwalsh]

Okay, so I'm looking for information on tankless heaters to replace a leaking hot water tank on one of my autos and an hour later, here I am fascinated by this thread. This is something I have wanted to do for a while but could never seem to get enough information. Thanks for taking all the time to help others out 2Biz.

One question I have is why the 20 degree differential on your aquastat?

All my floorheat systems are old Raypacks designed by Huron Valley with their air-x tank and giant Taco pumps. Has anyone successfully eliminated their Raypack with a tankless?

Go,

We plumbed in from our more efficient boilers on the laundromat side so boiler water goes through a Spirec Heat Exchanger to heat the antifreeze deicer side. We used Goldline digital controls for the turn ons & turn offs. We use a Weber (St. Louis Company) pump that has extra high lift to go through the Spirec. We gain efficiency because the actual BTUs of the natural gas burning is not lowered by the specific gravity of the antifreeze. I remember the mechanical engineer involved was having a hard time finding a pump with enough lift way back in about 1991.

mike

 

[2Biz]

I forgot to mention I read somewhere that the condensate that comes off these High Efficiency Boilers is acidic and needs to be neutralized. So I made one up out of 3" PVC instead of buying it. See pictures below. You can put either Linmestone gravel or Marble Chips inside the tube to neutralize the water. You might want to put the chips inside a hose/stocking to keep the gravel from getting into the inlet and outlet tubes.

After getting it finished today, I was able to fire the boiler up and let it run. This thing puts out several gallons of condensate an hour, so I didn't want to take any chances with the acidic water and my cast iron drains. Outside temps are about 27° today and ice had already formed on the outside truck bay slab. The wind is blowing 40-50 mph! Within about 15 minutes, I had 75° temps coming back into the ER from the zones. With the boiler set on 130°, I get 100° tempered glycol going out to the bays. Its ran for about 2 hrs now and the Ice on the truck bay concrete is starting to break up and melt. I wasn't able to run the boiler last night because I didn't have the neutralizer done yet, so the slab was cold and froze over. So far so good.

The Neutralizer Filled with Limestone Chips:

Boiler set point 130° and actual temperature output from boiler 128°:

100° Tempered Glycol going out to the bays, 20 PSI System Pressure:

Return Temps of 75° within 15-20 minutes after startup.

 

[Sequoia]

Floor heat

I purchased a Knight/Lochinvar boiler from carwashboilers.com (Chris Rojas) and I am extremely pleased. I also replaced a Weben/Jarco 350k btu gas hog and my is there a difference.

In my case, I bought a 150k btu unit for 3 SS bays. The numbers penciled out needing only 105K btu but I overshot on size as I did not want to come up short and the boiler will auto-modulate down when the return water temp rises.

I checked on my unit a few days ago and it was keeping the slabs ice-free at only 20% modulation, or 30k btu's. At that rate it was barely below freezing of course. This unit also has a PC connection and I've tinkered with its operation on freezing nights from the warmth of my living room while adjusting it via my laptop.

This has been one of the best improvements I've made to the wash .... and customer service from Chris has been excellent.

 

[2Biz]

I checked on my unit a few days ago and it was keeping the slabs ice-free at only 20% modulation, or 30k btu's. At that rate it was barely below freezing of course. This unit also has a PC connection and I've tinkered with its operation on freezing nights from the warmth of my living room while adjusting it via my laptop.

Being able to see the percentage of modulation would be a very nice feature. Mine doesn't have that although it does modulate....It would also be nice to log on and see how it was doing from home too! Nice...I looked at the Night/Lochinvar, but it didn't fit in my budget!

It will be interesting to compare cost to operate between the Takagi and the old Jarco...I'm sure it will be significant.

 

[2Biz]

It has been cold enough the past week to run the floor heat enough to evaluate and make changes in temp settings. What I've learned is, or this is my perception, I probably could have done without the return aquastat. Since these new boilers are modulating, I don't know if its wise to have the boiler cycling on/off based on return temps. When it cycles on/off, the boiler has to work a lot harder to bring the zones back up to temperature depending on differential setting. I think it makes more sense to find a boiler temp set point that keeps the floors from freezing, and let it run continuously at a very low modulated btu output. This keeps the boiler from running at a very high btu output when cycling on and off....Basically since the boiler can modulate, it does the job that an aquastat did with the old boilers that run at full btu rating. So I think I could have done without installing this feature. When the outside air temp gets above 33°, it turns everything off anyway, so theres no danger of overheating the system. Comments welcome....

So I lowered the boiler temp to 110° last night before coming home. This morning I had 76° return temps and 95° (tempered) temps going out to the bays. All the bays were perfectly clear, no ice. My weep goes across the floor and into the drains as I don't have piping for my weep water. There were some chunks of ice (Left from cars/trucks) that were melting on the floors at 20° outside temps...So this new system is working quite well so far. Temps are supposed to go down to 10° in the next 5 days. We'll see how it does then...

 

[Bubbles Galore]

I'm interested in your first NG bill to see the savings with the new system and project how long the payback will end up being.

 

[Sequoia]

Modulation

If you did not have a return aquastat, how would your boiler decide when to modulate down to lower BTU usage?

Maybe the Knight unit is different, but I thought that it sensed the temp of the return water and when that return water temp reached a pre-set level (that the operator can fiddle with) then it starts modulating down to keep the temp at that level but not let if fall.

 

[2Biz]

The control board monitors the incoming water temp and compares to the boiler set point. Then modulates based on the temperature spread. The farther apart the spread, the more BTU output is needed to close the spread. The closer the spread, the BTU's are decreased.

I lowered the boiler set point temp this morning even lower, down to 105° since I was going to be working at the wash and could monitor it. The outside temperature was about 28° and with the boiler set at 105° I was getting 75° return temps, 90-95° back out to the bays. Basically the boiler only had to raise the temperature from 75° to 105° or a difference of 30°. It modulates to the correct BTU to maintain this 30° temperature difference and the GPM flow through the boiler. If I were to raise the boiler set point, and still had 75° returning temperature, then the control board would increase BTU output to meet the load. Even at 105° set point the aquastat kicked off the boiler pumps at 76° and stayed off for about 30 minutes untill the return temps hit 55-60° before cycling back on. I checked and it only took a few minutes to get the return temps back to over 70° so having the aquastat do its job will help with gas usage...Surely...So I guess its good to have it inline for when the temps hover around 28-32°. It does allow the boiler to cycle on/off affectively....

 

[2Biz]

Update:

I got to the wash this morning and it was 8° outside. All (4) bay slabs, even the outside truck bay, did not have any ice on them with weep water running to the drain. I checked the boiler and had 76° return glycol temps and 90°tempered glycol going to bays with boiler set at 105°. It doesn't seem to work any harder at 8° as it does at 30°, same temperature spreads. So far its working better than I thought it would. We should be getting our NG bill soon. We had 25 out of 31 days in this billing cycle with temps below freezing. I let it cycle and run continuously below 33°.

 

[mjwalsh]

Update:

I got to the wash this morning and it was 8° outside. All (4) bay slabs, even the outside truck bay, did not have any ice on them with weep water running to the drain. I checked the boiler and had 76° return glycol temps and 90°tempered glycol going to bays with boiler set at 105°. It doesn't seem to work any harder at 8° as it does at 30°, same temperature spreads. So far its working better than I thought it would. We should be getting our NG bill soon. We had 25 out of 31 days in this billing cycle with temps below freezing. I let it cycle and run continuously below 33°.

2Biz,

Question: How do you get the degree symbol to show so I do not have to type out degrees

Some of us are in the -30 degree design area. Maybe some Canadian Operators are in even lower ... not sure. The wind chills have been going down below -40 lately here which affects the outdoor portions of the deicer.

Just an observation ... we notice that if the area where the slabstat becomes wet ... the deicer comes on earlier & stays on longer. That maybe could be a factor in why your system seems to run the same at both temperature levels.

mike

 

[2Biz]

Question: How do you get the degree symbol to show so I do not have to type out degrees

Hold down the "ALT" key while pressing the "0176" keys on the number keypad.

I don't have a slab stat. I can only monitor and cycle my boiler pumps and boiler with an aquastat on the return lines from the bays. It seems to be working ok...The only adjustments I have left is lowering the boiler temp another 5° and lowering the aquastat temp. Right now the boiler pumps cycle off at about 77° and cycles back on at 57°. I have a 20° temperature differential set on the aquastat.

 

[2Biz]

OK...I promised I'd give you an update when I rec'd my first Duke Energy NG bill. Keep in mind I also heat my ER with a 45K NG ceiling mounted furnace, set at 60°....The bill was from Dec. 17th to Jan 21st. - 35 days of service. Over 30 of those days it was below freezing . The past 5 days hasn't been above freezing any time of the day and as cold as 5° at night, so the boiler has ran 24 hrs a day. I have it set to come on at 33° from the secondary output on the weepmizer.

My total bill was $283.00. $110 of that was Fixed Delivery Charges and Gas Delivery Rider charges "Commercial Rates". I get charged that every month whether I use any or not.....I used 278 CCF in that time frame which equates to 27,800 cubic feet of NG. I'm guessing $50 a month is a good number to just heat the ER.

So....The addition of the new floor heat boiler cost me appr. $123 to run it over 30 days in this time frame. Needless to say, if I would have run the OLD DINASOUR 350K Jarco Webn this amount of time, I would have had to take out a second mortgage to pay the NG bill...I will also see similar savings in my electric bill, I went from 10a of 220v to 6 amps of 120v on the pumps....It is working perfectly...We had 1" of snow last night and my truck bay is perfectly clear, melting the snow as it came down, 20° outside..

 

[Buzzie8]

I want to do this. I know this would probably be a lot of work but if you could shoot a video of the install and post to youtube it would be great. I can edit video if you want and put model numbers, pricing, etc.. If you have an Iphone it takes great video (better than my expensive camera).
Thanks,
Buzzie

 

[Bubbles Galore]

Wow, that is extremely impressive. I am going to have to take a trip south to visit you this summer and evaluate the install to see how it would work for me. Kudos on the great job and the cost savings!

 

[2Biz]

I'll see what I can do about the video. I have a digital camera, so just need to get it out and charge the batteries! They are always low...But in the meantime, I've documented the install quite well if you have time to read through all the pages?!?!? There are photos on pages 3 and 5 that shows it completed and with the acid neutralizer installed. You might research this more and find a boiler without internal restrictions and get by with one pump and even a smaller pump.

Here is a list of some of the big ticket items...I ordered everything from Pexuniverse.com and pexsupply.com

Takagi 200K BTU Modulating Boiler T-H3-DV-N Boiler $1565.00
Isolation Valves TK-IV-01 $77.00
Taco 0013-F3 Cast Iron Pumps x 3 $241.00 ea
1" Air Eliminator VJR100 (Sits on top of Exp. Tank) $87.00
Rx 30 Exp. Tank for Glycol based systems $59.00
1" Threaded shutoff Freedom Swivel Flanges SF-100T x 2 $35.00 ea.

I used the heavy gauge 1" copper and all the other necessary Tee's, elbows and valves. (1/2" ball valves for zones)

One thing I might add, again, is whatever boiler you decide on, make sure you study the "Head Pressure" the unit has. This will help you install the right pump to supply glycol to the boiler. The Takagi boiler I bought is a commercial unit and is mainly designed to heat water. So the plumbing in the boiler is designed to run at water pressures up to 100 psi. So there are restrictions to overcome. Thats why I had to put two Taco 0013's in series to get at least 40 psi to the boiler. I get 7 gallons a minute flow through the boiler raising the temp appr. 30° which ,so far, has kept my bays, even outside bay, from freezing over.

I believe that using the Primary Secondary plumbing configuration is the best and should be incorporated into your design. It gives you way more flexibilty and control. You don't want to plumb your zones directly through the boiler, flow and control will be an issue. If you guys have any questions, I'll be happy to help.