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I love Combi's, but do any have stainless steel pumps..?

Newt Member Posts: 1
edited February 20 in THE MAIN WALL
We've installed hundreds of radiant floor heating systems (almost all 'non-Ferrous, pex, copper and Bronze pump) and will be transitioning some to Combi's and some to 'Hydronic Heat Pumps... (if you know what I mean... Air Source to Water Heat Pumps). Most of these utilize a primary pump to engage with the secondary AND also loop thru the on board DHW heat exchanger to provide hot water. Brilliant!... but I hate to add corrosion inhibitor just to protect the pump, if I could keep it as just plain beautiful water. Lower maintenance, no customer questions, no worry that it won't be replaced soon enough... Just simpler, just better. I will install gas fired combi's reluctantly (we don't need more climate change) but I vastly prefer to be lining up Hydronic Heat Pumps to do the job. Currently, I'm looking at a system in the country that would like backup if the electric grid goes down and a hydronic heat pump would be a bigger load than a propane boiler/instant heater. I don't seem to be able to find a Combi that has or allows a stainless steel pump to be installed... (UL listing issue)
HNY... Newt


  • Ironman
    Ironman Member Posts: 6,339
    Why do you think you need s SS pump or corrosion inhibitor in a closed loop system?
    Bob Boan
    You can choose to do what you want, but you cannot choose the consequences.
  • Derheatmeister
    Derheatmeister Member Posts: 1,003
    edited February 21
    No need for higher priced SS Circulators..
    We only use Stainless Steel Circulator when we are up against Non Oxygen barrier type tube that someone trying to save a dime installed...
    We do not recommend using Non Barrier type tube in hydronic heating systems and think for various reasons it should be against the code to use in closed loop hydronic heating systems.

    As to the system fluid:
    Nothing Plain and beautiful when "Just" using pain water in a hydronic heating systems !
    Higher maintenance,More customer questions later,More worries....More complicated,not better for the environment..higher carbon footprint because of premature failures to HX, Not having a manufactures warranty in place due to obuse,Premature failure of Circulating pumps,which again should not be warrantied,Premature failure of Piping systems,valves,Radiators,Stems,wasting more energy/Increasing your Carbon footprint/Annual fuel consumption due to deposits on the HX.
    Wasting more energy due to Sludge build up and therefor a bad transfer of energy and the list goes on.

    BTW.Corrosion inhibitors don't just protect the "Pumps".They protect the entire system !

    We also do NOT like using inhibitors/Chemicals !!

    For this reason we initially clean our systems and install deionized water in conjunction with a sacrificial anode as per VDI 2035...Less maintenance,Less customer questions,less worries about changing the depleted system fluid that has chemicals in it and "Just" dumping the heavy metal loaded chemicals down the drain like most of the heating/Plumbing Contractors do.
    Less worries about what these chemicals may do to the septic system including leach fields.
    Less worries about voiding boiler,circulating pumps,Fitting and other system components manufactures warranties.
    Less carbon footprint due to things mentioned above

    When we do our annual inspections,which everybody should,we just pull a system sample and analyze it for Clarity,PH and Electrical Conductivity.
    This is a very simple test that can be done in the field using a meter.
    We also check the possible depletion of the sacrificial anode via a meter and replace it if needed.
    Does not get simpler or "Greener" than this.
    Hope this helps explain why you should not need a Stainless Steel Circulating Pump... :)
    Richard From Heatmeister.

  • Newt
    Newt Member Posts: 1
    Hey there Richard (& Bob),
    Thanks for the replies. I can tell you gave it some effort. I appreciate your point of view but we DID spend more... on the pumps (all bronze). More $ than going barrier and using a steel pump...
    I might guess that Derheatmeister is an North Easterner (roll with it if that's even it it's not true... ) where for many years (centuries) 'traditional' hydronics was practiced... and still is. Cast Iron boilers and pumps and many other steel hydronic components and lots of CI radiators, well plumbed thru the years by dead men', may the RIP. Nice work, very functional I'm sure. I totally agree in that market that corrosion inhibitor is the way to go. No problem, no disagreement. We've been there, done that... I know there's some push back on using water heaters for heat sources but we've also used some Argos, HTP Munchkins, Lochinvar Knights, Buderous, H.S. Tarms and Naviens. We used them on a minority of jobs when the design parameters called for it. In earlier years (90s and 00s) I'd tell customers if money was tight, to put there money into a low temp tubing detail. That way, in the 'future' when energy prices go up you can replace your heat source with a direct solar source or an air source or ground source heat pump (indirect solar) and dramatically drop your operating cost and reduce environmental impact. If you have the money to do both, do both and also use a high efficiency heat source from the start (back then hi-ef gas). Along with tubing detail we'd emphasize a very well insulated construction/insulation detail 'encasing' the tubing detail to prevent costly heat loss over the decades. Electricity was $.05-6 per kWh back then, so it was very competitive with but still more than gas. Cheap energy will be the death of us (due to all the indirect costs...). Different story for electricity costs in most of the country, we have public power (BPA-Bonneville Power). Now we're at 8-9 cents and you all are at 10-20 cents/kWh. So you all have done oil first then gas for decades. Stupid to go electric resistance and spend big $$ monthly. Now, the start of the big push for electrification, so renewables can quickly replace the 'sin fuels'... all of us are 'sinners' (dig down towards hell, bring them up to paradise and burn it up... Sorry for the opinion but that's the way it is... & kind of an interesting simple view as well). The shift to electrification and heat pumps will be a boon to anyone who keeps up, including the boiler companies! After all, non steam boilers are water heaters really, while heat pumps are boilers... vaporizing the refrigerant working fluid to capture 'environmental energy' from the atmosphere. Cool huh..? I think so... Maybe boiler companies can start to colaborate with heat pump companies to build 'fired boosters' to allow heat pumps to do their job in their temp range but when you need a dragon to come in and get things toastier, get the fire breather!
    As well, with most of our projects we installed into super efficient green homes which can be heated with a (match..?.. no but a ) water heater with one element often, or two elements (simultaneous fire). Heat loss varies but between 12 btu to 20kbtu is not uncommon. In the past we did use an occasional Takagi (rated for heat) or Rinnai with a side arm heat exchanger... before combis were a thing. We also did some boilers with indirect W.H.s. Most boilers have firing rates of 50-100,000... ok add a buffer tank, and spend some more. Also, we found after the first 8-10 years that we rarely have leaks so we just plumb them isolated (like our solar water heaters) and put in a single larger expansion tank or add a second... We save the customer many $$ by avoiding the double back-flow AND the annual inspection. We often don't hear back from people for 10 years or more, and then it's just low pressure (LPCO) or a thermostat. Zip on maintenance... Saving customers hundreds of $$... yearly..(??.. yes). No rust anywhere... no iron... I have a long history in the solar thermal biz (where we always use cast iron pums!) and leaks are not tolerated and systems have to be isolated since they have glycol as freeze protection. Even water filled drain-backs have to be leak proof or the water evaps and pumps burn out. Our solar systems have run for 20 years with little maintenance... We're at the low temp side of Hydronics and from a different history... Ironically, from the HOTTEST side of the hydronics field... Solar hot water temps can easily swing between negative 10-20 all the way up to 300 degrees, so a boiler at ~~212, isn't much from our point of view and obviously if it isn't a steam system, you don't want it anywhere near 212. Sorry, I digress... I just thought it might be 'of interest' but I don't want to bore you either. Back to your thoughts...
    Yes, we have one or two jobs now and again that might shift to a different heat source with a cast iron pump (only ferrous metal in the system!). So, if we can't find an equivalent, we'll use Corrosion inhibitor, not a biggie. But if otherwise we can go 10 years between service calls, why not! Customers love our systems... Again, a different market, different approach. In the past we did some voyagers with flat plate heat exchangers and more recently the Phoenix high efficiency stainless steel solar tank with a Taco X-block, and it makes for a sweet efficient low operating cost heat source... and all non-ferrous. Don't get me wrong, I love rust... on the red planet Mars, it's covered in it (did you see the recent pictures of the surface taken by Perseverance... ( ). And I do like cast iron and steel for many uses, including heating systems... but for some, if there's no need then why saddle the customer with lifelong inspections and the potential for system failure... (of the worst kind- Leak, Flood or breakdown and NHC... no heat call).
    .... You say all these things and then ... the list goes on... but the proof is in the pudding... Our systems have stood the test of time. Again, I think you are right... from your perspective that I mentioned earlier. I could have done a better job of explaining what our market is... heck, we're in the 8-15 btu/ft heat loss market... you might be in the 15-40 btu market AND you may not even do low temp radiant... (??). Also, our design temp is 20 degrees... (EASY..!, we're spoiled compared to so many that face 10 degree or less design temps..). Sorry this was a bit of a ramble... disorganized but lots of info there... By the way... no sludge ever in our own systems...
    I really appreciate your comments at the end that line out your procedures in regards to your chemical use and methods. I'll copy your entire reply and file it for reference. cheers~ N (RPA member for many of the last 22 years..).
    Ps. To Bob, If your radiant floor heating system uses non barrier pex (anywhere) it will allow ‘air’ with oxygen content of ~21% to permeate into the fluid stream and if you have ferrous metals in the system the higher (and continuous) supply of oxygen will feed the rust machine (unless you use corrosion inhibitors).
  • Derheatmeister
    Derheatmeister Member Posts: 1,003
    edited February 21
    Wow....Can NOT roll with that..
    Sorry...Even though Der Heatmeister lived and practiced Hydronics on the east coast for a little while,My Roots are from Germany where i obtained most of my training ! Call me a Germerican.
    I stay in touch with my roots by revisiting and re educating myself on a regular basis.
    This will be the first IHS that i will not be attending due to the cancellation :'(
    Low temperature Radiant Solar Interfaces are something we Avocate,Design,Install and Maintain on a regular basis.. Nowadays ,where justified,we push drain for backs systems... :p
    We Install,Maintain and Service mainly High efficient Condensing boiler Installed at Elevations to about 11,200 feet.. :o
    Also been involved with Passive Solar Straw Bale Houses in Creststone Colorado <3
    I do not like Chemicals/Glycol/Inhibitor and try to avoid them when i can..Some people such as Mark E. and my wife are allowed to call me a "tree hugger".. :p
    Also,Member of the RPA ...and currently involved with one of the Technical Advisory committees.
    Looks like we may have more in common than you thought !
    One should Never Judge a Book by it's Cover. :)
    Respectfully submitted... Richard.
  • Ironman
    Ironman Member Posts: 6,339
    I never have and never will use non barrier tubing in a closed loop hydronic system.
    Bob Boan
    You can choose to do what you want, but you cannot choose the consequences.
  • Derheatmeister
    Derheatmeister Member Posts: 1,003
    BTW...The older Baxi Luna HT series ModCon boilers have a Grundfos with a Plastic Volute
    Not sure if the newer models still have the Plastic Volute.
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