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indirect water heater

Conventional water heaters usually require a monthly drainage of water from the bottom drain spigot to I suppose help eliminate any sediment , etc. An indirect with tank within tank construction, such as a W-M gold plus series 40, doesn't seem to require or have means to do same. Is this usual for an indirect, and why is this maintenance procedure of yore not necessary? I sent e-mail to W-M, but have received no explanation.


  • billtwocasebilltwocase Member Posts: 2,385

    indirects don't require this. That is more of a direct fired tank routine, Direct fired meaning electric, gas or oil fired tanks. In order to drain the Phase/Wm Plus tank, they need to be piped properly to suck the water out of them.
  • Bill H.Bill H. Member Posts: 30
    reply to Billtwocase

    I understand about the piping to enable sucking/syphoning the water. W-M seems to only mention doing so if winterizing the heater. There is no requirement for PERIODIC DRAINING ( monthly or annually )such as with a directly fired unit. My question is " why can this periodic maintenance be eliminated for an indirect?"
  • STEVEusaPASTEVEusaPA Member Posts: 4,444
    I think

    that's what billt was saying.  You dont need to do this with an indirect.  Keep in mind if you do need to do this, each manufacturer has specific instructions regarding what needs to be drained first to avoid damaging the indirect.  Depending on their construction, some need the boiler loop drained first, others need the domestic drained first.

    Hopefully Larry W. will chime on (he literally wrote the book), and would give you the technical reason why.  If he or someone else, doesnt respond by tonite, when I get home I'll pull his book out and give you a better answer.
  • billtwocasebilltwocase Member Posts: 2,385
    I would

    filter the incoming water to keep any sediment out of the tank. Most sediment adheres to the coils, or heat transfer source from the boiler. If you depressurize the domestic side of that particular indirect, you must depressurize the boiler side as well. 
  • Larry WeingartenLarry Weingarten Member Posts: 1,918

    Hello:  Heating drives hardness out of the water, forming sediment, but it happens only where the heat transfer is taking place.  An indirect removes that heat transfer function from the storage, so should have little in it to flush out unless there is sand/mud in the water supply, or perhaps the pump could move sediment from the heat exchanger into the tank.  I'd still pipe it so it could be cleaned out, but would expect a lot less gunk.  Where sediment interferes with heat transfer, like in an underfired heater, it can have unhappy side effects :~(

    Yours,  Larry
  • Bill H.Bill H. Member Posts: 30
    Reply to Larry

    What you describe makes sense to me. Unfortunately, now you have me wondering what becomes of the residue at the heat exchanger ( I assume you mean the boiler )? Perhaps the sediment stops precipitating sometime after the initial boiler fill, unless new water is introduced. I am assuming a "permanent " boiler fill with no leaks, etc. Am I thinking correctly?  Thanks to you, and to all others who have commented.   Bill
  • Larry WeingartenLarry Weingarten Member Posts: 1,918
    The heat exchanger...

    ... can be at the boiler or in the indirect.  Wherever it is, boiler water is on one side and fresh water on the other.  The boiler water has only a little hardness in it to start and basically can't have sediment problems unless there is a leak in the system (just as you say).  It's the fresh water side of things that can cause problems.  There have been lots of stories here about tankless coils liming up.  The tank within a tank you're looking at puts the heat transfer at the tank, but it uses a very large surface area for heat exchange.  This reduces sediment creation.  Still, if you have hard water, I'd want to be sure the indirect could be flushed. Clear as sediment?

    Yours,  Larry
  • Bill H.Bill H. Member Posts: 30
    Reply to Larry

    Clear as ultra-filtered spring water. Great explanation. I thank you. Don't ever go into politics, as you probably wouldn't be good at giving nebulus answers, which is a job requirement.     Bill
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