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code man says my DHW tank has to go as a heat source What now?

1246

Comments

  • archibald tuttle
    archibald tuttle Member Posts: 1,101
    professionalism

    gordy,



    i agree that a degree of caution is in order as between conceptualizing an off label use for a combustion unit (or electric heater although that is inapplicable in this thread) and recommending it as a professionally endorsed or certified solution.



    but i don't view those two as coterminus -- to use a favorite 4 syllable adjective. Indeed, several professionals recently recommended using domestic hot water heaters for radiant for a friend of mine who is a contractor, they know him, and they know it will work and they don't feel there is any comprise in safety.  they are trying to help him to channel resources towards the most efficient insulation and radiant installation and away from investing in expensive heating plant for the time being.  He has plenty of electric and that is actually what they are looking at. Cheap, easily replaceable. Efficient but the cost per btu is higher because of the cost of delivery.  But manageable given the sophistication of insulation and 'element' he is planning to install. If the hot water heaters crap out in 5 years, he can choose to upgrade then, or just throw in another $200 unit and keep going -- looking at what actual consumption has been and the relative costs of electricity and propane (or fuel oil, think the energy fundamentals and combustion technology don't favor it for the next decade at least, but i never say never.) 



    So those are the professional opinions he is getting, but that is distinct from certification. I think it would be the responsibility of professionals who see that certification is arbitrarily preventing a perfectly functional and safe arrangement from being employed to propose changing those standards.  Just as doctors can prescribe off-label uses for pharmaceuticals, a well informed professional -- or for that matter an educated homeowner with documenation -- should be able to work with inspectors to accomplish these ends.



    In that vein I appreciate Mark's suggestion to simply add a potential domestic use to the system as a way to legitimize it -- even though he recommends against actually employing the unit for the full domestic supply -- some stupid thing about the american foreign legionella or something.  There he goes thinking again.



    In a sense he is using the certification against itself. If rules are rules he is showing how you can follow the rules and get this done, while also suggesting full consideration of options.  That is professionalism -- not to mention paying it forward because we aren't paying him to be here.



    I hope he feels that he gains much from articulating solutions and this exhange of graffiti on the wall.  I certainly appreciate it, and try myself whenever i come here (or any other forum like it) with a question of my own to contribute to other threads.



    so i do go through absences when i ain't got any questions and could be helping (well maybe that is too generous a characterization of my 'contributions').



    I still think Mark's recommendation could be your best bet to solve problem for now while you consider your future 'powerplant'.



    brian
  • SWEI
    SWEI Member Posts: 7,356
    edited October 2013
    Mixing down

    under ODR control is well-proven at this point and it really does work better.  Comfort (minimized overshoot) and efficiency (longer firing cycles) both benefit from it.  A Taco iSeries-R is probably the simplest and least expensive way to get there.



    If you implement it, you can change heat sources (from a water heater to a CI boiler to a wood-fired boiler or even active solar thermal) without throwing it away.  It decouples the distribution loop from the heat source.



    Read this if you get serious about wood http://www.caleffi.us/en_US/caleffi/Details/Magazines/pdf/idronics_10_us.pdf
  • archibald tuttle
    archibald tuttle Member Posts: 1,101
    what about the takagi remote for JRII that morpho has linked

    I am not familiar with the  TK-RE02 remote control for the takagi. checked their installation manual, http://www.takagi.com/download/product_manuals/T-KJr.pdf , and they have a schematic on page 20 for heating install.  again, they say you may have to add other safety devices they don't show in the verbiage but they do not mention anything about 'certification'.



    maybe they are think american market and not really addressing canada and this is not as much of a problem here. for once we're more competitive in our regulatory structure if that were the case . . . on the other hand we'll never access our tar sands. god bless america . . . eeer alberta.



    I can't tell because they don't seem to easily link to install instructions for the remote which is very sophisticated, costs $40 and may even be included these days, and could easily house the capability for setback, but i can't tell if it does. it has in/out temperature input but that may be in coming and outgoing water rather than ambient air.  unclear on that and can't find install manual.  if they are going to show heating use and have that great modulation ability, i would think they would include a heating algorithm in this device, but i don't know if they do.



    and while it does give you some facility to do your own setback work conveniently without sensors, it only goes down to 99 degrees which is not as useful.  would be an awesome unit in combination with storage or mixing to obtain cooler temps for zone service, but it ought to have this stuff on board.



    brian
  • Gordy
    Gordy Member Posts: 9,546
    Another approach

    The human body at rest distributes 500 btus.



    I see you have two dogs. I would have to say that's at least another 1000 btus.



    Some assorted live stock could meet the load. The thermostat would be the occupant letting them in and out of the dwelling as needed.



    Seriously though this thread is turning into creative ways and methods to side step proper design practice, and codes.



    Gordy
  • archibald tuttle
    archibald tuttle Member Posts: 1,101
    gordy, see my other response on professionalism or i'll reiterate

    most of what people (perhaps other than me) are suggesting are ways to use the rules to allow him to continue to use a perfectly adequate and safe system.  that isn't getting around the rules, that is following them.



    as i said, mark's suggestion is by far the best, albeit if you believe that the rules bubble up the best of what the profession has to offer and somebody has been told the rules require a different combustion unit and they find a way to avoid that you may somehow think this is cyncism or avoiding the rules, i suggest it is anything but.



    further, as i mentioned in previous post,  as doctors can prescribe off label uses for drugs, i see no incompatibility whatsoever with that respect for medical professionals and the notion that heating professionals applying their knowledge and experience can construct safe uses for heating appliances that are not necessarily their design uses.  Esp. where the number of circumstances that might employ this technique are more limited it is understandable that manufacturers don't have incentive to certify or label such approaches but that doesn't suggest that what is being discussed here is inappropriate, unsafe or unprofessional.



    not to mention that this is quite obviously accepted practice in the states as it literally came up as a recommendation on a job i'm helping with from other professionals, besides this off the wall . . . occasionally on this wall . . . fellow who doesn't have a lot of respect for rules. honest, i didn't bring it up, i just chimed in and said i thought it was a great idea.



      i've got respect for the dangerous, unreliable or ineffective circumstances that rules are sometimes trying to avoid, i just don't believe that the rules usually represent the only or even the best ways to avoid them.



    brian





     
  • SWEI
    SWEI Member Posts: 7,356
    Professionals applying their experience

    on a job where they are making money and with familiar codes and inspectors is one thing.  Their reputation and their insurance are on the line and they make decisions accordingly.



    Advising someone you have not met, in a jurisdiction where you do not hold a license is something else entirely.  If you think we're conservative, try asking a PE.
  • Gordy
    Gordy Member Posts: 9,546
    Not only that

    People have a tendency to pick and choose bits and pieces of information that satisfy a subconscious thirst for getting a system they can afford. Not realizing that putting those bits, and pieces together in the wrong form can result in danger, and disaster. Kinda like Mentos, and a two liter pop bottle some aluminum foil.......





    People come here pick and choose parts of threads to come up with their own concoction of RFH.
  • SWEI
    SWEI Member Posts: 7,356
    Lochinvar Cadet

    Is a new line, with simpler controls and lower cost than the Knight series.  It's based on a Giannoni heat exchanger, which requires a bit more care in both installation and maintenance than the newer fire-tube HX designs.  BUT, it modulates down to 9,000 BTU/hr which is lower than anything else on the market.  It also costs about 30% less than either the WHN-055 (minimum modulation 11,000 BTU/hr) and the Viessmann 200-W B2HA 19 (12,000 BTU/hr minimum.)  It's not a general-purpose replacement for either of those, but for the money, it's a nice little unit.
  • morpho
    morpho Member Posts: 89
    And in Summary….

    Hey guy's..or ladies…never to sure on the cybernets.



    I just wanted to thank every last one of you for the input and on thoughts and design ideas.

    Code approved or not.



    My stated goal this whole time was to do what was safe and code approved. Several options were presented that "twisted" the codes intended meaning. i.e. Marks single, never to be used tap. And as I mentioned, the Government folks here in Alberta reiterated this approach as a solution as well.



    But my intention isn't to pull one over on em', I just want to make warm water and push it through the floor in a code approved safe way.



    If that involves a dual purpose tank cool. Or a Tankless unit that is approved and that functions well ….well thats cool as well.

    If I can get a boiler that fits the need and doesn't mean I drive my car and waste gas getting to a second job so I can pay for my "efficient" boiler and it's ongoing maintenance…well thats cool as well.



    All my questions regarding Tankless or Storage type systems was to understand the reasons they are or are not a good choice and why. Same goes for my dumb questions about boilers. If I had gone with the local suggestion from a gas fitter I would have a massive boiler that would be shot in no time flat. So this has been a great exercise for me to educate myself about the limits of what is possible, what is efficient, doable, safe and ultimately what will be code approved.



    Hey Gordy:

    Exactly where do I put the "outgoing" and "incoming" copper lines in the dogs?…….oh…..nevermind.



    Come here Abbie…good dog…stay still……
  • SWEI
    SWEI Member Posts: 7,356
    One basic decision

    which you really should make at this point is whether you intend to use a non-modulating heat source going forward.  The means pretty much anything other than a gas-fired mod/con boiler or a modulating electric boiler.  Wood, coal, solar, or a water heater (tanked or tankless.)  If so, you would be well-served to install an ODR-controlled mixing valve like a Taco iSeries-R.  It will serve any or all of those heat sources, even combinations of them.  If you decide on a modulating boiler, it will come with ODR controls onboard, which will obviate the need for this (and save you about $300-350 USD.)



    Best of luck with your system.
  • Gordy
    Gordy Member Posts: 9,546
    No tubing needed

    They are there own contained radiant heat source. If you want more output just play fetch for an hour.



    Sorry just being facetious Morpho . But have you ever been in a dairy barn milking cows?
  • Eastman
    Eastman Member Posts: 927
    hot water from compost pile

    http://www.motherearthnews.com/renewable-energy/compost-water-heater-zmaz81jazraw.aspx#axzz2itSsqGMY
  • Eastman
    Eastman Member Posts: 927
    What solution are you leaning to?

    Just curious what people get out of these threads.  
  • morpho
    morpho Member Posts: 89
    ?

    Gordy:

    Dairy cows in my house!? No way!

    I prefer goats.

    I read a book by a lady about how she built a greenhouse and she kept chickens if I remember correctly in it. She had their BTU output all factored in. Pretty cool stuff.

    I think it was called SOLVIVA…one sec…… http://www.solviva.com.



    Eastman:

    Funny you should mention compost heat. I have read a bit about it, but I can't get my pile up past 90….100 My goal is to get her into the 140 range so I can kill off the weed seeds etc, but I just can't get the carbon/nitrogen/moisture mix right.

    When I checked the thermometer a couple of days ago it was about 80 and falling.



    My plan was to use the compost pile to "heat" the cistern water in winter so it doesn't freeze up or get too cold for my tankless. But this hasn't proven to be a problem thus far. The water seems to have enough thermal mass and it is inside a passive solar greenhouse that gets pretty hot during the sunny winter days and over two years it hasn't frozen yet. (Fingers crossed)



    What am I going to do for a boiler you ask?



    I don't know. I thought I knew. Last night I was dead set on a CI boiler because it is low(er) tech compared to the Modcons, less power, probably less expensive to maintain etc. But they are all pretty much over powered for my needs.



    Modcon? Power hogs, Pricey, maintenance, unknown lifespan, even finding someone to service the thing will be a problem way out here. But space savings would be great, a few of them fit closer to my load minimums and the corrosion is less of a problem.



    The HWT is still possible, but I really don't like the idea of having to have it hooked up to the domestic water in any way shape or form. It takes up a bunch of space and I don't like the idea of having to be worried that the guts are rotting out of the thing. Easier to replace parts on CI boiler if they are corroding. I could drop big bucks on a stainless Polaris tank, but that requires big bucks!



    Wood? I would consider it if I could get my neighbour to come by every day for weeks on end to feed it while I am away. Not likely. They are pretty expensive to buy and instal as well.



    Tankless? I think it would work, but the cost on a certified unit puts me in the range of a CI boiler (maybe more once funky controls are added) and I'm not sure it would work any better. And there isn't much in the way of service techs once again.



    So, what did I get out of this forum experience….

    Tons!!!

    I can at least speak to the problem with a slightly more rounded understanding.

    Rounded…rounded…kinda the same meaning as obtuse. Hmmmmm?
  • SWEI
    SWEI Member Posts: 7,356
    Small CI boilers

    do exist.



    Chris pointed me at the Crown AWR038 awhile back, which is supposed to tolerate 110ºF return temps.  Too bad they don't offer a high altitude version or I'd be using them regularly here.
  • morpho
    morpho Member Posts: 89
    I am too high…just a bit

    2421 feet above sea level is where I am at….Maybe if I dig a pit 400 feet deep and drop the boiler down there it will work!



    Whats the worst that could happen with the boiler at 400 feet above the altitude limit?

    I see in the states they just de-rate it by 4%…hmmm….maybe I should be building a tower, not a pit!



    Anybody ever built an 8000 foot tall Boiler stand?
  • Eastman
    Eastman Member Posts: 927
    follow up on earlier suggestion

    FYI, I looked through the manual of the loch solution I had suggested earlier.  From my reading, the "performance loop" protects the unit from low system flow conditions, but not low temperatures.  So some kind of low temperature protection method would be a necessary addition.
  • SWEI
    SWEI Member Posts: 7,356
    Performance Loop

    as I understand, it was originally intended to deal with both flow and return temps, but did not perform as they had hoped.  Page 27 of the IOM does give conditions under which it can be eliminated.  I'd do that and install a thermostatic boiler protection valve (which we now specify for all conventional boilers.)  I like the 2-stage firing -- would sure like to see more of that in the market. 
  • RobG
    RobG Member Posts: 1,850
    How about this

    I think everyone agrees that what you are doing is operating safely and doing so in the best way possible for your situation. Until the manufactures catch up with the low BTU's required for these new highly insulated homes you are stuck (the power needs of your home are a whole different issue)  The codes for your area just do not take into account for your unique situation. Using a water heater as heat source is commonly done here in the U.S. , many jurisdictions still allow open systems doing both domestic and space heating.

    That said, how about using a vented gas wall heater and call that your main heat source for inspection. Try leaving the radiant hooked up for the inspection and tell him that it is just a project you are working on. He may make you disconnect the water heater but a couple of pex couplings to reconnect the radiant is a cheap price to pay. When boilers finally catch up with the lower BTU needs of many, you can always replace the water heater. As a bonus, the direct vent units will work with no power. If your solar ever goes down you have an alternate heat source and freeze protection.

    Just a thought.

    Just do a search on Google under "vented gas space heater" and you will find plenty.

    Good Luck,

    Rob

     
  • morpho
    morpho Member Posts: 89
    edited October 2013
    loop

    Eastman - SWEI

    Thanks for the info guy's……



    RobG - Huh…I will look up what these are about.

    Thanks
  • SWEI
    SWEI Member Posts: 7,356
    I was just about to suggest

    on of these http://www.rinnai.us/direct-vent-wall-furnace
  • morpho
    morpho Member Posts: 89
    Does anyone

    Have a good link or a thread to look back at that explains the hows and calculations for using a ci boiler…lets say a run of the mill "small" 50k btu unit. running into a heat exchanger….so that the other side of the exchanger is supplying the desired temp for the floor and keeping the system water and the boiler water separated.

    A constant one water temp kind of set-up. Nothing fancy, nothing involving computers or power.



    You guys know what I mean…I just can't explain it well.



    Yes I am positive the boiler will short cycle…(unless you have a way up your sleeves to cool the water going back into the boiler…but not too much as that makes it condense….)
  • Zman
    Zman Member Posts: 7,610
    Mixing valve

    Just run the water through a thermostatic mixing valve. It just has a manual knob to adjust the fixed temp to the slab. The boiler will be oversized so I don't think it will condense.

    You will be running the floor water temp a bit hotter than normal in order to reduce the heating cycle length and save electricity. You will see some overshoot of the t stat set point, that is the trade off.

    You have a very unusual condition that calls for some compromises and unusual solutions.

    Carl
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • Eastman
    Eastman Member Posts: 927
    just to clarify

    Do you have o2 barrier tubing?  
  • morpho
    morpho Member Posts: 89
    and there is the problem...

    ….well one of them anyway!



    I didn't know at the time to even ask about o2 barrier pex. It wasn't anything to do with trying to save a buck or anything….I simply didn't know any better. The loch solution has copper fin…maybe that will make it a bit less likely to be an issue?



    But this is life, Its in the slab and thats all there is to it and I will have to design around it.



    That dang Cadet begins to look good once in a while….actually a lot.



    A comedy of errors around here. •••hanging my head in shame•••



    How big an issue has this actually been for people?

    Has this not been a problem long before pex appeared?

    Was it just a fact of life and taken as a given?
  • Eastman
    Eastman Member Posts: 927
    edited October 2013
    o2

    I suspect it's not a big deal in small low temperature system like yours, but I think this information is something that you would want people to be aware of as they provide feedback.



    And once again, are you saying the tubing is not o2 barrier, or you don't know if it is or isn't?
  • morpho
    morpho Member Posts: 89
    BUBBLES!

    Not o2 barrier.

    confirmed.

    Sorry.
  • SWEI
    SWEI Member Posts: 7,356
    Heat exchanger

    If you install a reverse indirect, it will get the job done and provide some thermal mass buffer for the boiler.



    You just reached the point where I believe it will actually to be cheaper to install the mod/con.
  • morpho
    morpho Member Posts: 89
    And here is some sage advice from MORPHO

    Anyone who is following this thread or who may stumble across it in the search for info about the how's, why's and what's of radiant heat design and execution.



    Either:



    1. Read a lot and make sure you have all your ducks in a row. And then read some more and epoxy those ducks in place!



    2. Find a pro and pay em for their vast experience and Knowledge.



    3. Apply to University…don't….I repeat DON'T take liberal arts…get an Engineering Degree….design your heating system….post answers to heating help.com to save dumb people like me.



    So SWEI:

    Figure I'm to that place huh?

    I'd have to figure out what the ongoing maintenance cost of mod con is. Plus the price difference between a CI boiler.



    v.s.



    What the cost of just either replacing the exchanger on a CI and/or just replacing the CI boiler after ten years…….hahahahaha….I'm sorry! It's a habit. or maybe just bad genes. Maybe both.
  • Gordy
    Gordy Member Posts: 9,546
    No o2 barrier

    Is not a loss you just have to design around it. That means isolating the boiler from the tubing via heat exchanger.



    Or using non ferrous components. Ss, or bronze circulator



    And or using a boiler with a ss hx.



    If you don't the oxygen that diffuses through the non barrier tubing will corrode all the ferrous components in the system over time. There are o2 scavenger treatments that can be added to the fluid in your system also.



    Most boiler manufactures have notes about the use of non barrier tubing voiding warranties.





    As a side note ci boilers are very robust when properly installed.
  • Zman
    Zman Member Posts: 7,610
    Mod/Con

    With the O2 issue, the mod/con just moved up on the list. When you figure both the cost and the electrical usage of adding the heat exchanger and associated expansion tank, piping, air eliminator and circulator, a mod/con with a stainless circ and expansion tank is looking pretty good. The O2 is not the end of the world, just one more thing.

    Carl
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • Eastman
    Eastman Member Posts: 927
    edited October 2013
    understanding o2 diffusion

    http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=3&ved=0CDgQFjAC&url=http%3A%2F%2Fwww.mrpexsystems.com%2Fpdf%2FDiffusion.pdf&ei=uOhtUqm1Kebg2QXk_oG4DA&usg=AFQjCNHWNHKT2jqqYPTXiNpRqwLkug5zAQ&bvm=bv.55123115,d.b2I&cad=rja



    How bad of a problem is this?  My search came up with a Mr Pex doc that references a lot of German/euro research.



    Quoting the above referenced doc:



     "Experience from heating systems have since long established that corrosion levels in hydronic systems with ferrous metals are acceptable at the level one exchange of the system water (to fresh water) per annum."



    Apparently this is about .05 grams per cubic meter per day.  Regular plastic without the o2 barrier let's in much more.  The following is based on a water temperature of 104 F.



    "Typically, non-barrier plastic tubing allows about 5 grams [5 grams per cubic meter per day] to enter; 50 times more than allowable." 



    (This doesn't make any sense to me.  It seems like the diffusion rate would be a function of surface area, not volume of water.)



    So at a relatively low temperature you still get about 50 times the oxygen.



    Nothing in the doc says what the diffusion rate is per square foot of pex, though.  So how does one determine if they are exceeding 0.05 grams per cubic meter of water or not?



    Doc goes on to to suggest that systems with lots of steel versus plastic are still good.  And, believe it or not, that technically 1500 feet of marginally o2 barrier tubing is above one exchange of system water per year.
  • Eastman
    Eastman Member Posts: 927
    what I got out of this was

    You probably want a boiler that is impervious to rust, or you want an over sized CI unit that can handle a reasonable amount of corrosion spread out over it's surface area.  The copper tube boiler I mentioned still has cast iron joining the copper tube segments.  Without knowing all the details of its construction, my instinct is that this makes it a poor candidate.
  • Gordy
    Gordy Member Posts: 9,546
    edited October 2013
    Like Carl

    Said the mod/con with SS HX just moved up the list. You don't want any corrosion fouling the system.



    A bigger CI boiler only adds more surface area to corrode. You would have to isolate it via a heat exchanger, and that gives another hit to efficiency.



    My comment on CI boilers being robust was only intended on longevity compared to a mod/con when properly installed.



    I'm sure if you did a search on the wall of non barrier tubing issues there is plenty of ugly on here.
  • archibald tuttle
    archibald tuttle Member Posts: 1,101
    well, not to worry about the O2 barrier . . .

    . . . you'll be rotting the tank from the inside (dissolved oxygen) and the outside (exhaust condensation) at the same time. I'm still a fan of RobGs solution.  find someone who wants a propane wall heater. put that in.  get your propane delivered.  then go back to you old system.   high 5s rob.



     because you don't have oxygen barrier tubing, that should tip you in the long run, towards a storage tank with a heat exchanging coil that separates the water in the floor loops from the water in the boiler/heater.  And this will allow you more flexibility to use small CI boiler or say an old heatmaker which is very servicable low mass boiler but not modulating or condensing.  i think the lowest firing rate was 60,000m.  or i did find some cute little cast irons , http://www.younits.com/boilers-c-163_168.html?buto=40000&bufrom=30000 , including the Crowns mentioned already in this thread, but also a 'new yorker' at 27,000 btu which is nice and small and would team with a storage tank nicely.



    One advantage to cast iron boiler for your situation is that, same as the hot water heat you are using,  negligible or no electric consumption. The heatmaker or any mod-con will consume power because it uses fan forced combustion air. now that is one thing not mentioned in the blower door test question.  you need makeup air for the atmospherics - the modcons and heatmaker use outside air..  probably your house is not so tight that this small burners can't do it, but that is another reason to stick with a relativley low btu heating plant if you are going to stay atmospheric.



     but the 27000 btu CI atmospheric at $1200 -- and i would think you ought to be able to find it  a little cheaper than that, i didn't even look too hard -- ought to be a lifetime boiler if you separate the floor water and the boiler water with a storage tank. you might need a little clever piping to try to keep return temps from being too low that might actually start to look a little sensible. and on electric consumption side, you'd only need the boiler pump loop the hours the boiler is running and those hours would be minimized with more btus and storage.



    but far be it from me to discourage you from just  planning to buy a  $300 hot water heater every 3 or 4 years and keep on trucking with what you've got; and if you can't get the propane company happy with delivery what about the other idea i had, i.e., getting a half dozen or so hundred pound cylinders and finding a propane company that would give you a bulk price for filling those all at once?



    just because enquiring minds want to know, what does your $800 current bills and $400 expected bills under bulk contract actually amount to in terms of price per gallon or per pound?



    brian
  • SWEI
    SWEI Member Posts: 7,356
    It seems like the diffusion rate would be a function of surface area

    For a given tubing type (SDR9 PEX, in this case) the ratio of water volume to PEX volume is essentially constant.  The larger the pipe diameter, the less surface area per unit of water volume, but the PEX gets proportionally thicker to handle the pressure.  Since diffusion is a function of vapor pressure, it's going to track pretty closely.
  • morpho
    morpho Member Posts: 89
    edited October 2013
    Ok….

    The mod con army wins the battle!

    This is what I am going to do.

    Period!

    Honest!

    No waffling!

    Firm!

    Cadet.



    So, now that all other things have been eliminated, is there an ideal way to plumb this kind of setup? I keep seeing this. Why are both the in and out water lines connected side by side to the parallel line the expansion tank is on?

    Is this "the" way or is there even better ways to do it?
  • morpho
    morpho Member Posts: 89
    anybody want

    to buy a slightly used HWT?

    Works great!
  • Gordy
    Gordy Member Posts: 9,546
    All it means is it.

    Buy time before corrosion rears it's ugly head
  • Gordy
    Gordy Member Posts: 9,546
    Primary secondary

    Piping is the diagram.



    Basically the primary loop , and the secondary loop are decoupled by the closely spaced t's.



    This way the two loops can pump at different flow rates, and not effect one another.



    The cadet has a high head heat exchanger which may require a different flow rate than your heating loop.



    The primary loop is the loop with the expansion tank. The secondary loop is the loop for the boiler.



    Not to confuse you but the boiler loop could be the primary loop if the expansion tank were plumbed in at that loop.



    So in a nut she'll most signify the primary loop as which ever loop has the expansion tank.

    But yet some signify the primary loop as the boiler loop.
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