Reinstallation necessities?

Discussion in 'Water Heater Forum, Tanks' started by kcodyjr, Nov 25, 2013.

  1. kcodyjr

    kcodyjr New Member

    Messages:
    103
    Location:
    Chelmsford, MA
    For those who haven't seen one of my other threads about it, the hot water tank in my mobile home is presently sitting idle and empty in a corner while I rebuild the subfloor beneath it. That isn't done yet, but parts take time to ship, and I'd like to be ready with the plan sooner rather than later.

    The original install was a hack job to say the least, and has to get cut in half to allow the new subflooring in, so I'm starting from scratch and reworking the entire closet, including the entry and heating and pipes leaving the area. The system will also be getting a two stage filter, a PRV, and a backflow preventer, but let's ignore all that and focus on hot stuff.

    I've already ordered a vacuum relief valve, expansion tank, isolation valves, and a proper electrical whip. Also, I've gotten a pressure/temp gauge to sit right on top of the heater. I'm comparing models of master mixing valve (Watts LFMMVM1-US is looking good right now, the Honeywell isn't lead free) and there will be another temp gauge just after it.

    So, here's a list of "I think" that I'd like to hear others' thoughts on.

    I'm thinking to just use before-and-after valves on the entire hot water apparatus, so there wouldn't be more shutoffs around the mixing valve.

    I'm thinking the vacuum valve and temp/pressure gauge will be mounted on stubs right at the top of the heater, and the rest of it will be mounted on the wall.

    I think I want nice flexible braided hoses attaching the heater stubs to the wall mounted parts, but I'm not sure what the advantages of the flexible corrugated stuff might be in comparison. I know I don't want the heater hard piped, not even with unions.

    I think I want to put a pair of bent nose valves right above where the flex hoses attach to the wall piping, so I can let bulk amounts of air in while draining, and let air out at the highest point in the system, and tap the premixed hot water if I really need some.

    I think I want a check valve between the main cold pipe and the hot section to absolutely prevent heated water from ever coming back into the cold system, but I'm not sure if a single check would do or if it should be a real double-check backflow preventer. I think it should be a swing type, not a spring.

    Please, any of those "think" that spell DIYer about to shoot himself in foot, hit me with it before I put on new shoes.

    Anything else I haven't thought of is also open for debate - and, thanks in advance!
  2. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,313
    Location:
    New England
    The flexible (corrugated) copper supply lines (and any flexible lines) should be considered one time use things. They become harder after bending and sitting there for awhile, and you risk cracking them if you try to reuse them later. Not sure how much use the check valve would be, it may be a viable option but many people just use the heat traps that often come with the WH.

    From a functional perspective, the expansion tank must not have any valve between it and the WH, or it may not be able to perform its task (the only way would be if those valves either leaked, or were kept open, which isn't a certainty).
  3. kcodyjr

    kcodyjr New Member

    Messages:
    103
    Location:
    Chelmsford, MA

    OK, flexible corrugated lines are out, assuming the braided hose type are indeed reusable. Access is tight, I want to be able to get the tank out easily if I have to screw with any of the piping behind it, or to service the sacrificial anode.

    The cold-entry shutoff valve would be just before a union, in turn just upstream of the check valve. The hot-exit shutoff would be right next to that, also with a union just upstream (physically above) so that I can outright remove the entire heating section without affecting the cold water system. All the rest of the hot water related goodies would sit between those two ball valves.

    The purpose of the check valve is to absolutely prevent heated water from making it to a cold tap, ever, even if the expansion tank bites the dust. I'd rather have it pop the T&P in that situation. Watts' LF6 or LF601 are looking like good choices at the moment.

    I don't have anything that came with the WH, it's effectively a "used" unit. As I understand, a heat trap simply means placing the hot inlet of the 1017 tempering valve 8 or so inches below the top of the WH, so the water has to come up, over, and down before meeting the colder valve. If I've got it wrong, please, this is exactly the kind of bullet hole in the foot I'm afraid of.
  4. kcodyjr

    kcodyjr New Member

    Messages:
    103
    Location:
    Chelmsford, MA
    Followup, another "think" changed. I couldn't find a combined temp/press gauge that I liked, so they'll be separate. Pressure gauge atop the cold stub, temperature gauge on the hot, vacuum valve teed between the pressure gauge and flex hose.

    Another note about the check valve, if the expansion tank did fail and consequently sent a hot water sandwich down the cold pipe, it would be at tank temperature of 140 rather than the 120 coming down the hot pipe. Extreme scald risk right where it's least expected, and the ASSE1070 valve under the sink would do nothing to stop it. One check valve is easier to maintain than several overtemp shutoffs.
  5. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    27,237
    Location:
    Cave Creek, Arizona
    quote; the Honeywell isn't lead free

    Does that mean you intend to drink the hot water, since "lead free" items only apply to "potable water"? ALL of your "thinks" spell "do it yourselfer". The braided lines have a surgical or rubber tube inside them which has a higher chance of rupturing than a flexible stainless steel or copper line. Before and after valves have almost no value in a single family residence. A "vacuum relief valve" is also useless unless the tank in mounted in an attic of a multiple story building. Unless the gauge is mounted directly ON THE TANK it will not give a correct temperature reading. You can do the same thing with the T&P valve on the heater as you can with a "bent nose valve" on the hot water discharge pipe, other than get "full temperature water", if you ever needed it. Few installations need a check valve on the heater inlet, and NONE of them need a "double check". Spring or swing check is immaterial.
    Last edited: Nov 28, 2013
  6. kcodyjr

    kcodyjr New Member

    Messages:
    103
    Location:
    Chelmsford, MA
    Of course they say do-it-yourselfer. The question was, where do they say trouble.

    Re: drink the hot water. Perhaps indirectly, via cooking and washing dishes. I don't want that stuff on my plates. There's also the inescapable fact that my 2-year-old will get it in her mouth while bathing.

    Re: flex lines. Chance of rupture versus chance of cracking. Hm. I'll have to think on that awhile.

    Re: before and after valves. Then why has every residence I've ever seen had some means of isolating the hot system? Because tanks fail, and people like being able to flush the can while they wait for a new one.

    Re: vacuum relief valve. They are absolutely required in Massachusetts. It's not even a code/regulation, it's an actual act-of-Congress law. For what it's worth, I've heard it actuate while draining the tank.

    Re: temp gauge on the tank. It would be directly above the outlet, about 4 inches away from the top of the tank. Is that close enough? I realize the water will need to be flowing for an accurate reading.

    Re: tap valve. I don't see how the T&P valve can let air in or out of the system since it's nowhere near the top of the system, and everything I read about them says not to use them routinely because they stop closing after awhile. Am I to understand that last little bit of air in the tee to the expansion tank isn't a problem?

    Re: double check. Okay, simple check or none at all. I see stories all the time about people getting scalding hot water through their cold tap. Expansion tanks discourage but do not reliably prevent this: the additional pressure still has to go somewhere as soon as the system opens. Do you have a better approach to this?

    Thanks for the review.

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