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Oil boiler DHW among other "issues"



  • icesailor
    icesailor Member Posts: 7,265

    And I am correct in assuming that you used a single lever in this first floor bathroom?

    I'm in FLA right now. W. Palm Beach/Wellington/Royal Palm Beach area. They have no water tanks to provide head pressure. Just pumps pushing into something and variable speed pumps after the treatment tanks.

    We have a one floor condo type unit. The water pressure in the shower is so high that it really hurts your body. You'll see.
  • ice4life1417
    ice4life1417 Member Posts: 30

    absolutely a single handle and i'm jealous...i wish i had water pressure like that.
  • icesailor
    icesailor Member Posts: 7,265
    Pressure "Issues"

    No you do not. It is so high that even my wife complains. If you inadvertantly got shot in the eye in the shower, it could cause damage. And this is with the flow restrictors in. If I took them out, it would really be bad.
  • Ron Jr._3
    Ron Jr._3 Member Posts: 603
    Coming into the discussion a little late

    Our boiler installs are mainly with a coil and Watts 70A . What we've been finiding is the Watts , even set to the high 160 degree setting , is outputting only 120 degree water . With the boiler temp at 180 . Just something to keep in mind .

    But for pressure fluctuations I would suggest like a few others did . Take the mixer out and install an aquabooster on the system . You can control it like a indirect ( prioritize the bronze circ in a multizone relay and connect it all to outdoor reset if you wish ) . Hot side pressure should increase and be more steady if you pipe it like a System 2000 setup ( 4 pipes to the tank ) . Or you could just  " cold start " the system . Which will truly never be cold start since the tank will turn the boiler on several times a day even in summertime . Which really is a good thing with oil fired pin type boilers like yours and mine :)

    My oil boiler originally had a coil for hot water . I converted it to an indirect and outdoor reset and have been enjoying over 30 percent oil savings ever since . With the same boiler . I can guarantee it was not the indirect alone that accounts for all the savings .
  • icesailor
    icesailor Member Posts: 7,265

    Ron, in a sense, agrees with what I am saying. One that 70a's $uck. And maybe now, Watts is setting them to not go over 120 degrees because that is a new code standard fordomestic anti-scald hot water.

    However, if you do what he suggests and you aren't careful, if you get a call with a cold start, and the domestic hot water pump comes on without being wired to stop on cold, like a "low Limit" circulator setting would, you can "suck" all the hot water out of the hot water tank and it will be used to heat the house. Or, it is "transferred" to the heating water from where it had been stored for later use as domestic hot water.

    This is why you have "priority control" on these controllers. So you do not "suck out" all the stored hot water in the domestic hot water tank. if they both come on together.

    When you want hot water the most is in the AM when you get up, shower and get dressed, cook breakfast, do a load of clothes and run the dishwasher. And go off to work or school. AND you want to be warm and toasty. If during this time, any of these demandsare not met, because "The Cheapest" of the ones in the home want it so, will quickly find that "the one that desires the most comfort" will rule and all these techie ideas will be put to rest. Or at least when that person occupies the living space. I find that person to be the one with the longest hair, delivers the children and offspring of the same gender. There is nothing like the scorn of a woman in a cold shower with wet hair and soap that won't come out because of lack of cold water.

    As I have said before, Watts 70a's $uck. Maybe this is another reason they do now more than ever.
  • Ron Jr._3
    Ron Jr._3 Member Posts: 603
    Not an issue here

    with 2 women who take 30 min showers each am . After I take my 5 min scrub of the essentials .

    We always keep the priority on when a system has an indirect . Have not heard of one system needing to have the priority turned off , or the tank robbing the boiler of the btus so much it affects the hot water output . I guess it can be an issue somewhere , sometime . Just never heard of it yet . And like I said before in past threads .............. a cold start boiler isn't truly cold start if a hot water tank of some sort is connected to it . My own boiler has 115 degree water on the average when I wake up in the am . How many btus will be robbed from the boiler if the hot water tank is set at 120 ?????
  • Patchogue Phil_2
    Patchogue Phil_2 Member Posts: 303
    no mixing valve

    Personally,  I do not want a mixing valve right at the dhw source (whether it is a coil or otherwise).

    Dishwasher will use more electricity by heating the incoming hot water if it is not hot enough.  So you will want to send the dishwasher the hottest water you have.   Why heat the water very hot,  then blend it cooler and then heat it again (with electricity) at the dishwasher?

    I'd rather blend/mix at the point of use.

    My $0.02  
  • Patchogue Phil_2
    Patchogue Phil_2 Member Posts: 303

    I was hoping you will reply to my question?  Thanks.
  • icesailor
    icesailor Member Posts: 7,265
    Issues & Mixers:


    Here's the poop.

    Massachusetts led the way and now all code authorities deal with scalding in the same way. I don't know how CEA's deal with it in your area but, in mine, to get a final permit on plumbing installs, like a bathroom or water heater replacement, the CEA always checks the temperature of the hot water. It seems to go up and down but I think at the moment, it is 125 degrees. If the water coming out of a shower head is over 116'F, it is a failure. If the water coming out of a hot water faucet is over 125'F, it is a failure. Back when, electric was king and they wanted you to use all you could, it was determined that a 80 gallon was the best for family use. They started with 50's, switched it to 80's and had to drop back to 50's because they had origonally allowed the 50's. Their worry was running out of hot water. But, if you take a 50 gallon water heater and raise the tank temperature, you theoretically increase the size of the tank. If you think that this will do for a family, 50 gallons of 125' hot water, you will be surprised. They run out. But if you turn it up, you will fail. So, if you turn up the temperature in the tank, you increase the size of the tank, in theory. But if you install a Sparco mixer, on the water heater, and mix it back down, you can pass the 125 degree requirement and have more available hot water in the tank. A lot of places only have 40 or 30 gallon electrics. Electric's with 4500 watt elements only recover 18 gallons per hour. Regardless of the size of the tank. The Sparco/Honeywell unit is nice because it connects directly to the top of the water heater and has checks. Plus, it has a recirc. port.

    As far as dishwashers are concerned, they don't use that much hot water and the amount they use isn't all that much. And the cold water detergents work very well. If you let the heater heat the wash/rinse water, turn off the drying. The dishes will dry on their own from latent heat from the dishes and machine.

    Do the numbers. Pick your rise differential and the weight of the water. How many BTU's per hour to heat it. Say 2.5 GPM. Then, take the same in a heating situation. A 20 degree rise at 1 GPM. A domestic hot water heating load is way above residential heating.  I have a customer that has 2 Bock oil fired #73E's that are rated at 244.000 BTU's each at 1.75 GPH. They run out in an instant is not careful. 

    Remember, you do not recycle domestic hot water. Like you do in a heating system.  
  • icesailor
    icesailor Member Posts: 7,265


    If the 2.5 GPM flow restrictors are in place in the shower heads, that's 150 gallons per day for showers. More if the restrictors are removed.
  • D107
    D107 Member Posts: 1,810

    Is it legal to run an additional HW line off the HWH to the dishwasher taken before the mixing valve so dishwasher gets the 125 to 140 degree water --for those who don't want to use the dishwasher heater? I've seen this suggested on the wall before. Shouldn't be a scalding concern since it's only going inside the dishwasher.
  • Patchogue Phil_2
    Patchogue Phil_2 Member Posts: 303

    I appreciate you taking the time to reply.

    Do your inspectors allow the use of thermostatic mixing valves at each point of use (i.e. piping at each faucet)?  Or must the test be done close to the water heater output after any mixing valve at the tank?

    I have seen some houses plumbed where a 1/2 inch line is plumbed directly from the coil/WH (before any mixing valve) to the dishwasher and washer machine.  Then a separate pipe is plumbed AFTER the water heater mixing valve to all the other points of use in the house.  This way the washer machine and the dishwasher get the hottest water available.

    I prefer my boiler or WH heat the water high enough for the dishwasher,  rather than have the costly dishwasher electrical heating element perform the heating.  No matter how small the electrical savings,  it is worth it.  Especially in an area like mine where electricity is very expensive,  possibly highest in the US,  2nd to Hawaii.
  • Charlie from wmass
    Charlie from wmass Member Posts: 4,216
    That is how we do commercial and

    dormitory dish washers. With a dedicated hot water line.
    Cost is what you spend , value is what you get.

    cell # 413-841-6726
  • Jean-David Beyer
    Jean-David Beyer Member Posts: 2,666
    Ask the inspector.

    "Is it legal to run an additional HW line off the HWH to the dishwasher

    taken before the mixing valve so dishwasher gets the 125 to 140 degree


    I see it like that in the plumbing diagrams for my indirect hot water heater (W-M). They do not say you must do it this way. But they suggest it for the washing machine and diswasher.

    I do not think this important for the washing machine these days because modern detergents work quite well in cold water most of the time. Mine mixes hot water with the cold if the cold is under 60F. I do not have a mixer at the output of the hot water heater, that I run at about 125F at the heater. I measure the water coming out the nearest hot water tap and set the aquastat to give 120F water there. I guess code does not require a mixer.

    My water pipes are in the slab, along with the radiant heat (I think that was dumb). There is no practical way to run a separate pipe from the hot water heater.

    But my experience with inspectors is that no two agree on anything. Inspectors around here seem to be part-time, and have full-time jobs doing other things. All you can do is ask them. Do not ask more than one.

    If I wanted to run the indirect hotter, I think the thing to do is have the mixer valves near the point of use so the water in the pipes would be hot too. And insulate the pipes. People seem concerned about legionaires disease, but from what I read, you need hot water over 160F to get them. And I sure would not wish to touch water that hot.
  • Jean-David Beyer
    Jean-David Beyer Member Posts: 2,666
    Do your inspectors allow ...

    I am not a professional, and do not know the answer. I have two-stage (pressure and temperature) mixing valve in my darkroom that allows me to control the water temperature between some low temperature up to 105F +|- 1/2 degree (if the flow is above 1/2 gallon per minute). That is surely at the point of use. I estimate it is at least 40 feet from the water heater. But I do not know if an inspector has ever seen it, though a licensed plumber has. I have my doubts about that plumber though.

    If codes and inspectors were reasonable, it seems to me you could have mixing valves at the points of use, at least if you have them at all the points of use where people could get in contact with the water. Expensive, though. Around here, I guess mixing valves are not required, at least with electric hot water heaters, or indirect ones. Strange because I could set my indirect up to 160F if I wanted to just by turning the knob on the top of the tank. I do not know what the P/T valve is set to, but it is probably close to the boiling point: too hot to get on my hands. It is not the normal way to control water temperature. ;-)
  • icesailor
    icesailor Member Posts: 7,265

    A sepeate HW line to a DW and clothes washer is acceptable in all jusisdictions as far as I know.

    If 125 works for you, by all means, use it. It is when you have very small water storage tanks that run out of 125 degree water where you need higher temperatures. Or you have thermostatic single lever valves that need higher hot/cold differentials (hotter hot water) to work where you need it.

    Whatever works for you.
  • icesailor
    icesailor Member Posts: 7,265

    In Massachusetts, we are required to have 6 hours of Continuous Education with an approved source to renew our licenses. Inspectors do more. I think they do monthly classes with the State Board of Examiners of Plumbers and Gas Fitters. The Board is very serious about ALL the inspectors being on the same page as our code book. An inspector is not supposed to be able to say "I like to see it done THIS way." when the code book clearly says you can do it another way and you did it that way. You can now call the Board for an instant determination. It' made it a lot easier if you work in different towns. They also have "Depity Dawgs" sneaking around that can write you up for an insta violation. Like unsupervised apprentices on a job or worse, unregestered apprentices.

    The Continuing Education is worth every penny.
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