Another tankless water heater replacing boiler thread

[OurTown]

Since you are running 2 heaters, you'll get more flow and pressure with the 2400-45-3P than I'm getting with my (2) 013's....Did you check amperage on the 2400 series pump? Its 3.6a at 115v. Make sure your relays and aquastats handle the extra load. The 013's are only 2.0a. You'd think almost double the amps, you'd get double the volume and pressure!? LOL.....Probably like a boat, double the horse power and get a few more mph!

I'm trying to finalize the exact location of components in each loop. After looking at many diagrams it isn't very clear to me. Even though I have seen a few online diagrams that contradict this, I will call the boiler loop the primary and the floor tubing loop the secondary. Maybe there is a little flexibility on the exact location of a few of these components. I'll list where I think they go and you or others can agree or point me the correct way if not:

Primary loop:
The two pumps plumbed inline feed the cold side heater inlets.
Shut off valves on either side of the pump assembly
Pressure gauge between pumps and heaters
Temp gauge on hot side outlet going to the secondary loop

Secondary loop:
Single pump plumbed on hot outlet side of closely fitted tees that join the loops feeding outgoing floor tubing manifolds
Air eliminator plumbed between the pump and the closely fitted tees and boiler drains on each side for fill and purge (I have also seen this located on the primary loop)
Expansion tank plumbed into the bottom of the air separator if I have the space for that large assembly. Otherwise, I may plumb it elsewhere near the separator.
Mesh strainer between return cold line from manifolds and closely fitted tees (I have seen this in many different locations)
Shut off valves on either side of the pump
Temp gauge on the outgoing hot line to manifolds (not sure if it matters if it is before the pump or after)
Temp gauge on the return line from floor manifolds to mesh strainer/closely fitted tees
Primary pump temp control probe clamped to return line and insulated
Pressure gauge. Should this go on the hot supply going to the manifolds or cold return? I think it might show a little higher pressure on the outgoing side.
30 PSI pressure relief valve (^probably next to the system pressure gauge^)

I'm trying to keep as many components off the primary loop as reasonably possible. Using two heaters already complicates things with those parallel circuits going to each.

Other than isolating the pumps for maintenance where else should I plumb shut off valves? The air separator needs vertical orientation and the pump motor shafts need horizontal orientation with the electrical junction boxes on top. Are there any other components that orientation or gravity may play in?

 

[OurTown]

Oh, and another thing. I'm about $7,500 in so far.

 

[OurTown]

Has anyone studied the systems that this company offers? What I don't understand is how they can get the Takagi to work with only one pump. I thought I heard them say in one of their videos that the mixing valve they use plays into this.

https://www.radiantcompany.com/system/closedsystem/

 

[2Biz]

Has anyone studied the systems that this company offers? What I don't understand is how they can get the Takagi to work with only one pump. I thought I heard them say in one of their videos that the mixing valve they use plays into this.

https://www.radiantcompany.com/system/closedsystem/

I'll answer this one first....I have often wondered the same thing. I am wondering if the Grundfos pumps they use supply a higher pressure OR are they just running lower volume at higher temps? It muight be worth a call to them and ask the flow and pressure of the Grundfos pump they use? Our Takagi's will go up to 180° and maybe there is no difference in efficiency....BTUS in BTUS out...I tried higher temps on the Takagi and it caused it to short cycle. At 30°, the heater runs 15 minutes on 15 minutes off. The neat part is it is always a 30 minute on/off cycle, no matter how long the on cyucle is.....You have to keep in mind the Radiant Systems are much different than what we are running. They have pumps on each zone that keeps the living quarters within 1° set point. The heat transfer is much less than what we see, so they might be running a lot lower flow at higher temps???

 

[2Biz]

Answers in Bold Italic:

I'm trying to finalize the exact location of components in each loop. After looking at many diagrams it isn't very clear to me. Even though I have seen a few online diagrams that contradict this, I will call the boiler loop the primary and the floor tubing loop the secondary. Maybe there is a little flexibility on the exact location of a few of these components. I'll list where I think they go and you or others can agree or point me the correct way if not:

Primary loop:
The two pumps plumbed inline feed the cold side heater inlets. Yes
Shut off valves on either side of the pump assembly Yes
Pressure gauge between pumps and heaters One is not shown in the picture, but you can see the capped port just below the heater with the blue valve handle . I have a pressure gage attached to this port currently. The port is also used to purge air.
Temp gauge on hot side outlet going to the secondary loop Yes, you can see it in the photo

Secondary loop:
Single pump plumbed on hot outlet side of closely fitted tees that join the loops feeding outgoing floor tubing manifolds Yes
Air eliminator plumbed between the pump and the closely fitted tees and boiler drains on each side for fill and purge (I have also seen this located on the primary loop) Yes, although I would not use faucet style valves. I would use ball valves.
Expansion tank plumbed into the bottom of the air separator if I have the space for that large assembly. Otherwise, I may plumb it elsewhere near the separator. It can go anywhere. It doesn't have to be attached to the air seperator. Althought the fitting is there for the attachment of the Ex Tanks
Mesh strainer between return cold line from manifolds and closely fitted tees (I have seen this in many different locations) I see on the Radiant Systems site, they use one. But I didn't. There is a fine mesh strainer in the base of the inlet port of theheater. I've only had to clean this screen once in 10 years! I started my system this morning and it stil lthroughputs 6.0gpm through the heater, same as its always been. If there was an obstruction, it would slow the flow volume.
Shut off valves on either side of the pump Yes, so you can change out a pump cartridge without losing glycol
Temp gauge on the outgoing hot line to manifolds (not sure if it matters if it is before the pump or after), Yes, doesn't matter.
Temp gauge on the return line from floor manifolds to mesh strainer/closely fitted tees I like seeing what the return temps are with a mechanical gauge, but not necessary. You can see the return temps on the display of the heater by pushing the info button. It displays output temp, input temp, and flow throguhput.
Primary pump temp control probe clamped to return line and insulated Yes, needed to control on/off cycles of the Primary Pumps.
Pressure gauge. Should this go on the hot supply going to the manifolds or cold return? I think it might show a little higher pressure on the outgoing side. Yes, I have mine between the Ex Tank and the secondary pump going out to the bays.
30 PSI pressure relief valve (^probably next to the system pressure gauge^) My pressure relief safty valve is at the base of the heater. You can see it with the white pvc fitting on it. The fitting is now attached to the condensate drain and acid neutralizer then to the drain.

I'm trying to keep as many components off the primary loop as reasonably possible. Using two heaters already complicates things with those parallel circuits going to each.

Other than isolating the pumps for maintenance where else should I plumb shut off valves? The air separator needs vertical orientation and the pump motor shafts need horizontal orientation with the electrical junction boxes on top. Are there any other components that orientation or gravity may play in? You need a shutoff valve inbetween the two service valves as shown next to the EX Tank...You would benefit by putting the shutoff valves at the base of theheater like I have. They are needed for purging and I also use them to check pressure.

Here is a photo of my completed system for reference:

 

[2Biz]

For people following this thread, I like posting efficiency results of installing a system like this over paying out the A$$ for propane or NG with the old dinasour sytems we used to have....There were very few hours that the floor heat "Wasn't" running the whole 29 days in this billing cycle. 19 out of 29 days the minimum temp was below 15°, 7 days below 0° and coldest night was -15°....It was bitter cold and I didn't have a bay floor freeze. And I weep water across the floor and into the bay pitts.

2015 Coldest Month Numbers Are In

Date Range: Feb. 11th thru March 12th (29 days in Billing Cycle)

Temperatures:
21 days Max. temp was below 32°
29 days Min. temp was below 32°
19 days Min. Temp was below 15°
7 days Min. temp was below zero
Coldest night was -15°

NG usage in this billing cycle was 449ccf for a total of $440. The floor heat ran 100% of the time below 33°. I also added a 199K btu NG Water Heater that I didn’t have last winter. This usage includes the floor heat, 199K btu WH, 40K btu ceiling furnace, 2 burner wall heater that I run 1 burner below freezing and 2 burners below 15°…

One thing I did this year was lower my return glycol temp by 2°. That changed the amount of "ON" time the demand heater was seeing while still keeping the bays ice free. Its on the "Edge"! Even adding the WH and my total was less than last year with similar temps.

 

[OurTown]

Answers in Bold Italic:

I'm trying to finalize the exact location of components in each loop. After looking at many diagrams it isn't very clear to me. Even though I have seen a few online diagrams that contradict this, I will call the boiler loop the primary and the floor tubing loop the secondary. Maybe there is a little flexibility on the exact location of a few of these components. I'll list where I think they go and you or others can agree or point me the correct way if not:

Primary loop:
The two pumps plumbed inline feed the cold side heater inlets. Yes
Shut off valves on either side of the pump assembly Yes
Pressure gauge between pumps and heaters One is not shown in the picture, but you can see the capped port just below the heater with the blue valve handle . I have a pressure gage attached to this port currently. The port is also used to purge air.
Temp gauge on hot side outlet going to the secondary loop Yes, you can see it in the photo

Secondary loop:
Single pump plumbed on hot outlet side of closely fitted tees that join the loops feeding outgoing floor tubing manifolds Yes
Air eliminator plumbed between the pump and the closely fitted tees and boiler drains on each side for fill and purge (I have also seen this located on the primary loop) Yes, although I would not use faucet style valves. I would use ball valves.
Expansion tank plumbed into the bottom of the air separator if I have the space for that large assembly. Otherwise, I may plumb it elsewhere near the separator. It can go anywhere. It doesn't have to be attached to the air seperator. Althought the fitting is there for the attachment of the Ex Tanks
Mesh strainer between return cold line from manifolds and closely fitted tees (I have seen this in many different locations) I see on the Radiant Systems site, they use one. But I didn't. There is a fine mesh strainer in the base of the inlet port of theheater. I've only had to clean this screen once in 10 years! I started my system this morning and it stil lthroughputs 6.0gpm through the heater, same as its always been. If there was an obstruction, it would slow the flow volume.
Shut off valves on either side of the pump Yes, so you can change out a pump cartridge without losing glycol
Temp gauge on the outgoing hot line to manifolds (not sure if it matters if it is before the pump or after), Yes, doesn't matter.
Temp gauge on the return line from floor manifolds to mesh strainer/closely fitted tees I like seeing what the return temps are with a mechanical gauge, but not necessary. You can see the return temps on the display of the heater by pushing the info button. It displays output temp, input temp, and flow throguhput.
Primary pump temp control probe clamped to return line and insulated Yes, needed to control on/off cycles of the Primary Pumps.
Pressure gauge. Should this go on the hot supply going to the manifolds or cold return? I think it might show a little higher pressure on the outgoing side. Yes, I have mine between the Ex Tank and the secondary pump going out to the bays.
30 PSI pressure relief valve (^probably next to the system pressure gauge^) My pressure relief safty valve is at the base of the heater. You can see it with the white pvc fitting on it. The fitting is now attached to the condensate drain and acid neutralizer then to the drain.

I'm trying to keep as many components off the primary loop as reasonably possible. Using two heaters already complicates things with those parallel circuits going to each.

Other than isolating the pumps for maintenance where else should I plumb shut off valves? The air separator needs vertical orientation and the pump motor shafts need horizontal orientation with the electrical junction boxes on top. Are there any other components that orientation or gravity may play in? You need a shutoff valve inbetween the two service valves as shown next to the EX Tank...You would benefit by putting the shutoff valves at the base of theheater like I have. They are needed for purging and I also use them to check pressure.

Here is a photo of my completed system for reference:

Thanks!
Are you running the 150 psi T&P valve that came with the isolation kit or did you swap it out with a 30 psi valve? My plan is to keep those 150 psi valves on the isolation kits because I'm hoping to be above 30 psi feed pressure like yours is running. I want to have the 30 psi valve on the secondary loop where I'll monitor the 15-18 psi main pressure running in case something stupid happens.

 

[2Biz]

The output on the heater will not be at the same pressure as the inlet. The output will be the system pressure. I'll have to look tomorrow and see if I have the 150psi T&P valve....I'm pretty sure I didn't change it out. Also, I only run 10psi system pressure. Been that way ever since installation...I do not have a pressure relief valve on the secondary. You are only running about 90° max glycol...There is not much expansion at 90°...We arn't running boiler temps...But if it gives you the warm and fuzzies!

 

[2Biz]

Thanks!
Are you running the 150 psi T&P valve that came with the isolation kit or did you swap it out with a 30 psi valve? My plan is to keep those 150 psi valves on the isolation kits because I'm hoping to be above 30 psi feed pressure like yours is running. I want to have the 30 psi valve on the secondary loop where I'll monitor the 15-18 psi main pressure running in case something stupid happens.

I just chechked and my PRV is 150 psi...I don't think it would ever work as there would be a catestrophic failure somewhere else! LOL As mentioned earlier, I only heat the glycol to 90° in the secondary piping to the bays...Not much expansion...and I have the Expansion tank...You'll want to pressurize the tank at the same pressure you are running the system. I've had my system running 12 years now already. So must have done something right!!

 

[Roz]

systems are in series. They heat the floors and the troth. Right unit controls everything. Then at 80% of capacity it calls the second unit to respond. Each is 199K BTU. Closed loop. It measures the out flow and inflow glycol temps to see if heating level is adequate to keep floors above 34deg.

 

[Blanco]

View attachment 12271

systems are in series. They heat the floors and the troth. Right unit controls everything. Then at 80% of capacity it calls the second unit to respond. Each is 199K BTU. Closed loop. It measures the out flow and inflow glycol temps to see if heating level is adequate to keep floors above 34deg.

All that black pipe connecting to brass/copper mixed together is going to cause serious galvanic corrosion.

 

[2Biz]

Even though this is an awsome looking system, I agree with Blanco....You will definetly have issues with Galvanic Corrosion down the road because of the dissimilar metals where they touch each other.

I have first hand experience....My 2" water supply is heavy wall copper. Years ago, whoever put in the 2" water meter used cast iron flanges on both sides of the meter that came in contact with the copper. The water rates were such that I was paying a minimum of 33,000 gallons a month for both water and sewage when I was always using less than 20,000 gallons. (Can't believe the PO didn't correct this!) I inquired and discovered I could reduce the meter size to 1" (still giving me 40 gpm more than doubling my max gpm usage) and my minimum dropped to 2000 gallons a month. While changing out the meter I discovered the incoming water supply was restricted to about a dime size hole because of the galvanic corrosion of the two dissimilar metals. Granted, they probably didn't even know about the issue when it was first installed, but we know now...So its best not to mix metals when designing or building systems like this. The worst you should ever do is put Copper and Brass together. Thats why they are listed next to each other in the tables for minimal reaction. I would have never figured out low flow rates if I wouldn't have torn into it to correct the $$$ issue! This is one of the few times I didn't have to learn the hard way!

 

[Roz]

View attachment 12271

systems are in series. They heat the floors and the troth. Right unit controls everything. Then at 80% of capacity it calls the second unit to respond. Each is 199K BTU. Closed loop. It measures the out flow and inflow glycol temps to see if heating level is adequate to keep floors above 34deg.

I will ask my master plumber about the pipe types as he did all the work (at different times) for me. Thx for raising the question.

 

[OurTown]

Even though this is an awsome looking system, I agree with Blanco....You will definetly have issues with Galvanic Corrosion down the road because of the dissimilar metals where they touch each other.

I have first hand experience....My 2" water supply is heavy wall copper. Years ago, whoever put in the 2" water meter used cast iron flanges on both sides of the meter that came in contact with the copper. The water rates were such that I was paying a minimum of 33,000 gallons a month for both water and sewage when I was always using less than 20,000 gallons. (Can't believe the PO didn't correct this!) I inquired and discovered I could reduce the meter size to 1" (still giving me 40 gpm more than doubling my max gpm usage) and my minimum dropped to 2000 gallons a month. While changing out the meter I discovered the incoming water supply was restricted to about a dime size hole because of the galvanic corrosion of the two dissimilar metals. Granted, they probably didn't even know about the issue when it was first installed, but we know now...So its best not to mix metals when designing or building systems like this. The worst you should ever do is put Copper and Brass together. Thats why they are listed next to each other in the tables for minimal reaction. I would have never figured out low flow rates if I wouldn't have torn into it to correct the $$$ issue! This is one of the few times I didn't have to learn the hard way!

The PEX tubing in the closed system is oxygen free to protect the cast iron pumps so maybe using the steel pipe is not as bad as you think. I wouldn't do it though.

 

[2Biz]

Galvanic Corrosion has nothing to do with the pex and oxygen free part to a degree. It has to do with the Milivolt current produced when two dissimilar metals touch and an electrolyte flows across the 2 different metals. Copied from Wikipedia that explains it better than from my memory:

Dissimilar metals and alloys have different electrode potentials, and when two or more come into contact in an electrolyte, one metal (that is more reactive) acts as anode and the other (that is less reactive) as cathode. The electropotential difference between the reactions at the two electrodes is the driving force for an accelerated attack on the anode metal, which dissolves into the electrolyte. This leads to the metal at the anode corroding more quickly than it otherwise would and corrosion at the cathode being inhibited. The presence of an electrolyte and an electrical conducting path between the metals is essential for galvanic corrosion to occur. The electrolyte provides a means for ion migration whereby ions move to prevent charge build-up that would otherwise stop the reaction. If the electrolyte contains only metal ions that are not easily reduced (such as Na+, Ca2+, K+, Mg2+, or Zn2+), the cathode reaction is the reduction of dissolved H+ to H2 or O2 to OH−.[1][2][3][4]

Then I just found this that kinda makes sense:

Then again, this is a closed-loop cooling circuit, correct? Then, provided no path for air to contact the fluid, any corrosion will progress only until the dissolved oxygen in the fluid is consumed.

Most sites still say to keep piping the same or at least with metals close to each other in the table, like brass and copper to keep galvanic corrosion minimal. Then there are corrosion inhibitors you can add....It can get as deep as you want!

 

[Blanco]

Galvanic Corrosion has nothing to do with the pex and oxygen free part to a degree. It has to do with the Milivolt current produced when two dissimilar metals touch and an electrolyte flows across the 2 different metals. Copied from Wikipedia that explains it better than from my memory:

Dissimilar metals and alloys have different electrode potentials, and when two or more come into contact in an electrolyte, one metal (that is more reactive) acts as anode and the other (that is less reactive) as cathode. The electropotential difference between the reactions at the two electrodes is the driving force for an accelerated attack on the anode metal, which dissolves into the electrolyte. This leads to the metal at the anode corroding more quickly than it otherwise would and corrosion at the cathode being inhibited. The presence of an electrolyte and an electrical conducting path between the metals is essential for galvanic corrosion to occur. The electrolyte provides a means for ion migration whereby ions move to prevent charge build-up that would otherwise stop the reaction. If the electrolyte contains only metal ions that are not easily reduced (such as Na+, Ca2+, K+, Mg2+, or Zn2+), the cathode reaction is the reduction of dissolved H+ to H2 or O2 to OH−.[1][2][3][4]

Then I just found this that kinda makes sense:

Then again, this is a closed-loop cooling circuit, correct? Then, provided no path for air to contact the fluid, any corrosion will progress only until the dissolved oxygen in the fluid is consumed.

Most sites still say to keep piping the same or at least with metals close to each other in the table, like brass and copper to keep galvanic corrosion minimal. Then there are corrosion inhibitors you can add....It can get as deep as you want!

Yes you never connect different metals. That is kindergarten plumbing basics. If you absolutely have to then you use what is called a dielectric union. In this case you can see the fitting on the right where the steel and copper meet is not and is clearly discolored. Although it is a closed loop system glycol which contains water acts as a conductor.

 

[OurTown]

Yes you never connect different metals. That is kindergarten plumbing basics. If you absolutely have to then you use what is called a dielectric union.

What about connecting copper male adapters to cast iron pump flanges?

 

[Blanco]

What about connecting copper male adapters to cast iron pump flanges?

Absolutely not on a potable/domestic water system. Definitely a code violation and your water will be brown in no time plus have issues like 2BIZ had with his meter. However I see this alot on older closed loop systems or hot water recirculation. Even in Roz photo you can see the green Taco cast iron flanges on Grundfos pumps which are most likely brass, stainless, or even cast iron. Why they still look brand new compared to the fittings that connect the copper to black pipe I do not know. In my own washes I use only brass/bronze pumps and flanges. For the washes I install/service I do not do the plumbing but i have seen plumbers that will use cast iron flanges then put a dielectric fitting on each side of the pump. Those are only the plumbers that actually care though. Few of them out there.

 

[OurTown]

Galvanic Corrosion has nothing to do with the pex and oxygen free part to a degree. It has to do with the Milivolt current produced when two dissimilar metals touch and an electrolyte flows across the 2 different metals. Copied from Wikipedia that explains it better than from my memory:

Dissimilar metals and alloys have different electrode potentials, and when two or more come into contact in an electrolyte, one metal (that is more reactive) acts as anode and the other (that is less reactive) as cathode. The electropotential difference between the reactions at the two electrodes is the driving force for an accelerated attack on the anode metal, which dissolves into the electrolyte. This leads to the metal at the anode corroding more quickly than it otherwise would and corrosion at the cathode being inhibited. The presence of an electrolyte and an electrical conducting path between the metals is essential for galvanic corrosion to occur. The electrolyte provides a means for ion migration whereby ions move to prevent charge build-up that would otherwise stop the reaction. If the electrolyte contains only metal ions that are not easily reduced (such as Na+, Ca2+, K+, Mg2+, or Zn2+), the cathode reaction is the reduction of dissolved H+ to H2 or O2 to OH−.[1][2][3][4]

Then I just found this that kinda makes sense:

Then again, this is a closed-loop cooling circuit, correct? Then, provided no path for air to contact the fluid, any corrosion will progress only until the dissolved oxygen in the fluid is consumed.

Most sites still say to keep piping the same or at least with metals close to each other in the table, like brass and copper to keep galvanic corrosion minimal. Then there are corrosion inhibitors you can add....It can get as deep as you want!

It looks like you have cast iron pump flanges with a brass nipple between the two pumps.

 

[OurTown]

Absolutely not on a potable/domestic water system. Definitely a code violation and your water will be brown in no time plus have issues like 2BIZ had with his meter. However I see this alot on older closed loop systems or hot water recirculation. Even in Roz photo you can see the green Taco cast iron flanges on Grundfos pumps which are most likely brass, stainless, or even cast iron. Why they still look brand new compared to the fittings that connect the copper to black pipe I do not know. In my own washes I use only brass/bronze pumps and flanges. For the washes I install/service I do not do the plumbing but i have seen plumbers that will use cast iron flanges then put a dielectric fitting on each side of the pump. Those are only the plumbers that actually care though. Few of them out there.

Our old DHW circulator had bronze pump flanges. I think the pump was even bronze because it was a painted brown Taco. The floor heat circulator (there was only one pump for the whole system) was cast iron and had cast iron flanges connected directly to copper. Super Wash built about 700 of these washes and our wash was one of their mid-later builds so I would think they would have remedied that by then if it was an issue. It looked and worked fine when I removed it and I think it was the original at 20 years old. It looks like 2Biz has cast iron flanges between his two pumps, and a brass nipple connects them. Most of the companies that sell the premade closed loop systems are using the bronze isolation valve flanges but I did see quite a few that had the regular cast iron flanges directly connected to copper or brass. It must not be a major issue. At least that is what I'm hoping because that is what I have on hand and the bronze flanges are three days out to get. I could order them and swap them out later but my experience is that I may have to fight them to get them to line up.