Another tankless water heater replacing boiler thread

[2Biz]

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

Good catch! Wonder how many years I have left?! My system just turned 12yo....The gpm through my heater has remained unchanged at 6.0gpm the entire time, even with the tiny passages in the Takagi Heat Exchanger....I think that reading would be a good value to monitor to see if/when an issue with corrosion is affecting how well the system works. If I remember correctly, the cost of brass or SS flanges and pump housings scared the hell out of me! My pockets wern't very deep then! I can only imagine the price now! I'm hoping the paint Taco uses is an isolator!!! Jk....

There is also a very fine mesh and tiny screen filter in the inlet to the heater. I posted I had issues in the beginning with this filter plugging because I ran a "cleaner" in the system before filling with propylene glycol....I ran a 5 micron filter in line for a day or two to filter the system. Since then, I have never had to take the small filter out to clean it....

Here is a short but good read that CantBreak80 just sent me...Explains a lot and some preventative measures you can take like maintaining propper PH to extend the systme life, even in a system with dissimilar metals.

How water behaves in hydronic systems - HPAC MagazineHPAC Magazine

 

[OurTown]

Good catch! Wonder how many years I have left?! My system just turned 12yo....The gpm through my heater has remained unchanged at 6.0gpm the entire time, even with the tiny passages in the Takagi Heat Exchanger....I think that reading would be a good value to monitor to see if/when an issue with corrosion is affecting how well the system works. If I remember correctly, the cost of brass or SS flanges and pump housings scared the hell out of me! My pockets wern't very deep then! I can only imagine the price now! I'm hoping the paint Taco uses is an isolator!!! Jk....

There is also a very fine mesh and tiny screen filter in the inlet to the heater. I posted I had issues in the beginning with this filter plugging because I ran a "cleaner" in the system before filling with propylene glycol....I ran a 5 micron filter in line for a day or two to filter the system. Since then, I have never had to take the small filter out to clean it....

Here is a short but good read that CantBreak80 just sent me...Explains a lot and some preventative measures you can take like maintaining propper PH to extend the systme life, even in a system with dissimilar metals.

How water behaves in hydronic systems - HPAC MagazineHPAC Magazine

Two sets of sweat brass isolation valve flanges and one set of sweat bronze flanges is $285 plus tax. If I order them between now and tomorrow before end of day they will be here Tuesday. Not ideal because if I don't have this up and running by Wednesday I will have to shut down again because of cold weather.

 

[2Biz]

No pressure here!

 

[Blanco]

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.

What size flanges do you need? Menards has them in stock up to 1" for $50. See attached. Dont know if you have one around you. Supply house has tons in stock. https://www.supplyhouse.com/Pump-Flanges-1836000. I prefer to do things once the right way. Nothing pisses me off more then having to do something twice. Super wash may have owned and built 700 washes but im going to guess there were hundreds of differant plumbers. Some washes might have got this while others got that all at the plumbers choice. If you have to use cast because of the tight pinch your in just use them to get up and running but I would change them out later on.