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Not enough hot water--need help!

Hi--thanks in advance to all who can help me.

Background: I am married with three girls. They take showers that are usually longer (wash hair!). Typically 2 showers run in my house at same time. We also have dishwasher, laundry, etc. But usually dont run together.

I have a lennox boiler with 113k btu output (140k btu input).
I had a separate gas hot water heater (GE 75 gallons). It turned 14 years old recently, and instead of it waiting to break, I decided to replace.
Doing some research, and hearing from some friends, I investigated installing an indirect hot water heater system. All the #s I saw showed that the output of the indirect would be greater than a gas hot water heater.

So I bit the bullet, had my boiler rewired with a priority switch, repiped to the new Heat-Flo 60 gallon I purchased. It included a mixing valve as well.

The mixing valve is set at 115 degrees F.

The Heat-Flo is set at the maximum 160 degrees F.

I had all plumbing and electric double checked.

The problem: when 2 showers are running, within 20 minutes, we run out of hot water! When I had my gas hot water heater this did not happen! I had the heat-flo inspected by the company to confirm there is nothing wrong with it. The only thing they could tell me is that even though my boiler is rated to put out 113k btus, its 13 years old and could be putting out less.
I am really upset. My family is so frustrated that we spent so much to switch over and yet we now have less hot water than we had previously with a seperate gas hot water heater. I am throwing my arms up at this point and giving up. My only last option is to rip out everything I did and go back to a seperate high-output gas hot water heater.

Hoping maybe the experts here could possibly come up with something to solve my issue!



  • JUGHNEJUGHNE Member Posts: 7,895
    You can clock the NG meter to see if the boiler actually has that input.
    When the hot water priory takes over: The boiler has to run up to a higher temp, (mine goes up to 180), It takes a good sized pump to move the boiler thru the tank heat exchanger.....more than you might use for house heating perhaps.
    Also all the water goes to the tank HXC, might use a heat flow check to keep the water directed to the HXC and not sneaking off into the house heating system.

    There may be a differential adjustment for the tank temp.....making it fire early before tank cools off too much.
  • DZoroDZoro Member Posts: 1,037
    Post some pictures of the entire set up. What model boiler, does it have outdoor reset system?
  • BobCBobC Member Posts: 5,172
    What size pipe to and from the indirect from the boiler/

    Smith G8-3 with EZ Gas @ 90,000 BTU, Single pipe steam
    Vaporstat with a 12oz cut-out and 4oz cut-in
    3PSI gauge
  • kuniskkunisk Member Posts: 21
    OK. Attached are some pics. The pipes I believe are 1". There is no meter outside showing how much gas I use. We checked the differential of when the boiler/circulator fires as the temp drops and it was very little.

  • Big Ed_4Big Ed_4 Member Posts: 1,572
    Four Ladies in the home :) .. The more you supply the longer they we take ... :) Install low volume shower heads, pace the showers or keeps adding storage ..Good luck my Friend
    I have enough experience to know , that I dont know it all
  • Jamie HallJamie Hall Member Posts: 14,877
    Let's think about this for a minute. 2 showers running together -- 5 gpm. For 20 minutes. That's 100 gallons of hot water, give or take. Now with the old 75 gallon heater, that meant you used the 75 gallons of nice hot water and had to make up 25 more over the 20 minutes -- or a bit more than 1 gpm. It takes 1 BTU to raise 1 pound of water 1 degree, so if we are looking at about 7 pounds of water going from say 40 to 110 we need something on the order of 500 BTU per minute, or 30,000 BTU per hour. No problem for the gas heater.

    Now with the indirect, we need about 40 gallons of makeup water; 2 gpm. So we need a minimum of 60,000 BTUh to handle the flow.

    So the question is -- is the indirect actually putting that much heat into the water? It might be worth measuring the supply and return water temperatures from your boiler, and the flow, to see...
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England.
    Hoffman Equipped System (all original except boiler), Weil-Mclain 580, 2.75 gph Carlin, Vapourstat 0.5 -- 6.0 ounces per square inch
    kuniskMark EathertonSuperTech
  • kuniskkunisk Member Posts: 21
    Jamie--My boiler is rated a 110k btu output. So even if its at 50% efficiency, it should hit close to 60k. Also the heat-flo gent that was here measured the temps on the pipes coming out and it was within the correct range.
    j a_2
  • kuniskkunisk Member Posts: 21
    someone I just spoke to suggested i spend a few hundred and add a small electric hot water tank next to the heat-flo. Said it would keep water at a warmer temp so when it goes through heat flo, the temp is already high. Said its like turbo charging your system. Interesting idea, not something I wanted to do or spend $ on, but looking for solutions.
    And as much as I would like to limit shower time, when the girls have friends over there is usually 2 showers going one after another!
    Mark Eatherton
  • DZoroDZoro Member Posts: 1,037
    On top of the storage tank is the mixing valve. One side is the hot in should be piped from the tank and a 90* turn into the mixing valve. During the high water use time/when they are running low on water. Feel that pipe to see if it is still very hot or not so hot. There maybe a temperature sticker on the mixing side of the valve, you could move that to the hot pipe coming out of the storage tank and monitor it that way. Just trying to confirm the entire tank is out of hot water. That pipe should also be labeled hot on the storage tank.
    kuniskrick in Alaska
  • BrewbeerBrewbeer Member Posts: 611
    Maybe undersized piping and or pump between the boiler and indirect?
    Hydronics inspired homeowner with self-designed high efficiency low temperature baseboard system and professionally installed mod-con boiler with indirect DHW. My system design thread:
    System Photo:
  • kuniskkunisk Member Posts: 21
    Dennis--I did check the pipe temp. As we run out of water in the showers, that pipe does get cooler. so it is indeed the tank running out of hot water.
    Brewbeer--I had both the plumber and the heatflo company check the circulator that pumps the return to the boiler to ensure its the correct one for my unit, Its a variable speed circulator. And yes they said it was correct. its set on the fastest speed which is what everyone recommended.
  • DZoroDZoro Member Posts: 1,037
    Is the priority switch on in the zone control. You have 4 total zones and a 2 zone controller. I'm assuming the domestic is on its own zone and it is the priority.
    kuniskMark Eatherton
  • DZoroDZoro Member Posts: 1,037
    Does the boiler maintain its 180* set point while heating the storage tank?
  • kuniskkunisk Member Posts: 21
    Dennis- the priority is on for the hot water circulator. I have two circulators. One for my heat circulator (which has three zone control valves) and one for my hot water circulator. The priority is set for my hot water circulator and i have tested this.
    The boiler goes between 170-180. As the boiler drops to 170 it turns on till reaching 180 again.
  • JUGHNEJUGHNE Member Posts: 7,895
    When it goes to DHW heating mode do the pipes on the top of the heating zone valves get hot say 2' up or so?
  • kuniskkunisk Member Posts: 21
    The pipes above the zone valve do not get hot. The pipes above the hot weater tank get scorching hot.
  • kcoppkcopp Member Posts: 3,602
    edited February 2018
    What is the circulator going to the WH? Heat flow actually recommends a 133k boiler to get you the listed HW outputs. What temp is the WH tank set at?
    My thought is there is not just 1 thing that is the problem but a number of small things that are leading to this. 75 gallons is still 15 gallons more that you have now.
  • DZoroDZoro Member Posts: 1,037
    May need to bring the boiler on quicker. Possibly with a flow sensor/timer? Or a more adjustable tank thermostat.
  • unclejohnunclejohn Member Posts: 1,689
    How do you get the air out of the boiler piping to the Heat Flow. I have a 40 gal. indirect and have never run out of hot water.
  • hot_rodhot_rod Member Posts: 14,394
    flow test a shower, see how many Gpm they actually flow. 2.5 gpm shower heads work great these days

    you have less dump with the smaller tank it seems that is the difference, assuming all is working correctly

    is the indirect coil piped properly
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    The magic is in hydronics, and hydronics is in me
  • SnowmeltSnowmelt Member Posts: 1,258
    I am going with hot rod on this one if the indirect water heater in 100,000 btu that's borderline 1 1/4 piping, if its piped with 3/4 (going to the boiler ) your going to run out every time. if you have one inch it would be close but no guarantee
  • MikeGMikeG Member Posts: 154
    What about using a larger electric water heater with a pump to gain more storage from the indirect. This isn't helping the recovery just giving more initial starting volume. May or may not even use one of the elements. Icesailor had a design for that. Electric water heaters are reasonably cheap not $100 bucks. Water conservation methods are still a good thing.
  • Mark EathertonMark Eatherton Member Posts: 5,837
    So, it sounds like its an air problem. Boiler is hot, supply and return lines from boiler are hot, but DHW is not... Missing link somewhere. The energy is being made, but not making it into the tank.

    Hard to tell from the angles given in the photos, but if you don't have a check valve in the DHW boiler circuit, you need one. Otherwise, when the space heating pump is on, fluid will be short circuiting through the DHW tank, losing that stored energy.

    I'd check temperature differentials on the boiler supply and return lines to the DHW tank, under load (running two shower heads at full flow) and near the end of the cycle. If working correctly, you should have a bigger delta T when under load than when it is nearly satisfying the tank set point. Check it where it leaves the boiler and returns back to the boiler, as well as where it goes into and comes out of the boiler side of the tank.

    You've got a slipping clutch somewhere...

    It's not so much a case of "You got what you paid for", as it is a matter of "You DIDN'T get what you DIDN'T pay for, and you're NOT going to get what you thought you were in the way of comfort". Borrowed from Heatboy.
  • hot_rodhot_rod Member Posts: 14,394
    dip tube in that tank?
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    The magic is in hydronics, and hydronics is in me
  • LanceLance Member Posts: 142
    Whoa, can I step back and look at this again? If this is the HF-60 the chart the manufacturer uses is a must read. At 180F boiler water the chart shows 4GPM continuous for 115F domestic.
    At 140F domestic we have 2.95GPM. But this is based on a 14 GPM flow rate from the boiler through the coil. The chart also reads this is based on a boiler output equal to at least 132,340 BTUH. You state yours is 113,000 BTUH. There isn't enough boiler output to meet the specs. So even if the tank is at max temp, and at this point I would want it on standby at 160F, with a mixing valve set at 120F you might just approach a satisfactory situation provided 3 GPM is not exceeded and you might just get the storage capacity equal to a 78 Gallon tank. All bets off if we exceed 3 gpm after drawing off the first 80 Gallons.
    I know this because this is what I do and I also have 3 daughters.
    I know a boiler has to be at 90% afue and have a min. 150,000 BTUH INPUT to maintain 3GPM to the shower head; but that is the limit. Any more draw than 3gpm will not keep up.
    When we see and do the engineering we can work the solutions.
    Your boiler heating needs are set for radiation temps? If this is below 180F you will have to reset this. Go up to 200F is the next option. If the boiler temp does not drop than the flow rate between tank and boiler is probably not 14 GPM. This is much higher than a normal heat zone which is usually 3-5GPM. Did the installer measure the flow rate, record and provide you the performance data? PS. All mfg ratings are based on 50F inlet cold water. In Maryland we spec for 40F cold water for winter. It makes a difference. In yesterdays world the building heat loads exceeded domestic hot water loads and the boiler was large enough. Today with smaller building heat loads the domestic hot water load is the greater. You would not believe how many jobs I see that lack the engineering, proper application and correct installation required to make it right. I have job security for many lifetimes ahead. my chart ref: Water Heaters - Spec Sheet.pdf
    j a_2SuperTech
  • JUGHNEJUGHNE Member Posts: 7,895
    It would seem too simple but would the boiler water in & out connections be switched? The cold needs a dip tube as Bob said above.
  • Jamie HallJamie Hall Member Posts: 14,877
    Seems to me that @Lance is saying exactly what I was saying -- but with more authority (always nice to be backed up!). The setup you have may just, plain and simple, not have the capacity...
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England.
    Hoffman Equipped System (all original except boiler), Weil-Mclain 580, 2.75 gph Carlin, Vapourstat 0.5 -- 6.0 ounces per square inch
    j a_2SuperTech
  • JUGHNEJUGHNE Member Posts: 7,895
    OP did state that doing DHW the boiler would cycle between 170-180........not getting rid of BTU's fast enough????

    If he needed more fire it seems the boiler would not cycle but slowly fall down in temp while constantly firing. FWIW
    Mark Eathertonrick in AlaskaZmanSuperTech
  • HomerJSmithHomerJSmith Member Posts: 1,103
    kunisk--to give you some idea of my system which might give you some insight into your system, I'll spell my system out.

    I have a 3200 sq' house with 3 baths, two of which is mostly used. I have a HTP Munchkin 140 M boiler and at my altitude, I have a 12% derating of the boiler output. So, I have about 123K BTU output.
    My boiler is connected to a 45 gal HTP indirect water tank. I never run out of hot water, ever. The boiler has a DHW priority over space heating. The boiler fires at 185 deg for the DWH and on Out Door Reset for space heating. The water storage in the tank is set at 150 deg with thermostatic mixing valve regulating the supply temp to the house at 120 deg. The tank is set by the boiler at a 5 deg differential. The cupro-nickel heat exchanger in the tank is 1".

    kunisk, your system and some ideas.

    What is the water temperature supplied by the boiler to your indirect tank?

    Does your boiler give priority to the indirect when it calls for heat?

    What is the indirect's Heat Exchanger size and the material it is made of?

    What is the make and model of the pump supplying the boiler water to the indirect and is the pump only supplying boiler water to the indirect and nothing else?

    Why set the thermostatic mixing valve set to 115 deg instead of 120 or 125 deg?

    What I think is based on those questions. Your boiler must be giving priority to the indirect when the indirect calls for heat over space heating. The aquastat on the tank must have a small differential and not 15 deg. It may be adjustable, set it for a tight differential. The pump must be capable of delivering the BTU's to the HX in the indirect. The flow thu the HX, and consequently the transfer of the BTU's from the boiler water to the tank water, is dependent upon several factors. The pumping power, the HX tube size and design, and the temperature of the boiler water.

    What I think may be happening to you to cause your problem is--
    The boiler water is too low a temperature and not a priority setup. The HX in the indirect is too small, so that the flow thru the HX is too slow, therefore, not transferring enough BTU's. The indirect pump is not powerful enough to increase the flow thru the HX. Your tank differential is too wide and set to a low a tank temp.

    I like a hot DHW temperature, just because it kills Legionnaires' disease bacteria.
  • HomerJSmithHomerJSmith Member Posts: 1,103
    One more thing, I always pump into the highest pressure loss and not away from it, that would be your indirect, I suspect.

    Personally, I don't think you have the flow thru the HX and that is certainly what I would want to know, first.
  • JUGHNEJUGHNE Member Posts: 7,895
    If all the piping is right I just have a gut feeling you don't have enough pump. Just a WAG.

    I built my own HXC from a scrap of 3' x 8" pipe from the farm iron pile. Put in 20' of 3/4" copper for a bundle. Initially with 100,000 input I would not run out of hot water with a house full.

    I changed boilers and from trial & error and just using the pumps available, I now have a smaller pump for the bundle and my recovery is much less. But with a 120 gallon tank and only 2 people we get along.
  • DZoroDZoro Member Posts: 1,037
    You mentioned the boiler pipes are scorching hot at the storage tank. Is the return 20* or so cooler than the supply? You could move the thermometer tape to those pipes, and confirm temps.

    It sounds like the boiler is having no problem keeping up. But is all of its power going to the storage tank.
    Do both of your pumps now have check valves in them? Or are there any in the system?
    A picture from farther away would help, we can zoom in on our side of the computer. :)
  • kuniskkunisk Member Posts: 21
    WOW! THank you everyone. Great responses.
    Here are some answers to some of the questions....

    --The circulator is a Taco 0015 MSF-IFC circulator with three speeds. Its set to the fastest one. The circulator only supplies to the hot water heater.

    --Hot water heater (Heat-flo 60) is set to 160 degrees. The mixing valve is set to 115 degrees.

    --Boiler does fire quickly after falling below 180 degrees at about 170 degrees. To me that means the hot water heater is getting hot water from the boiler. The aquastat is a honeywell and i replaced it already to confirm it is working properly.

    --I am not sure how the "air" gets out of hot water heater, although my plumber did say he bled the system for any air pockets and their is a check valve.

    --Indirect hot water heater is installed correctly. I had two other plumbers look at it.

    --Dip tube is welded on to unit per Heat-flo so unlikely an issue.

    --The hot water heater is on priority on the boiler.

    -Plumber said doesnt want to push boiler to 200, could cause issues in other areas.

    --Pipe size is 1" plumber said main is 3/4" so not going to have flow with higher pipe size.

    ***One thing that Lance mentioned. Heat-Flo chart says I need 132k output. I only have 113k. That is on me. I thought with 140k btu coming loss would be a small amount, not 20k. I mentioned this to my plumber and he said he strongly does not think its an issue as the water coming from boiler is extremely hot, any hotter is not going to help. He believes that for some reason the hot water flowing through the indirect is just not heating up the water fast enough (he doesnt love heat-flo, thinks its garbage but put it on based on my request). My last step is going to be putting a thermometer on the boiler return and supply to hot water heater so I can see the differential. This will help tell us if the heat-flo is doing its job.

    A HUGE THANK YOU TO EVERYONE FOR TRYING TO HELP! Keep the advice coming and any creative ideas on how I can get more hot water I am all ears as is my plumber (who is a friend of mine).

    Also attached is another pic.

  • BrewbeerBrewbeer Member Posts: 611
    --Pipe size is 1" plumber said main is 3/4" so not going to have flow with higher pipe size.

    This seems to be part of the problem, 3/4" pipe can't deliver the full load of the boiler that the indirect can accept.
    Hydronics inspired homeowner with self-designed high efficiency low temperature baseboard system and professionally installed mod-con boiler with indirect DHW. My system design thread:
    System Photo:
  • JUGHNEJUGHNE Member Posts: 7,895
    Isn't that full size 1" connections to the coil of the tank?
    Looking at the DHW piping next to it.
    1" to the top of the pump?
    1 1/4" below the pump?
    Just checking my senior eyes.
  • HomerJSmithHomerJSmith Member Posts: 1,103
    I was looking at the manual and your connections to the tank and I think you have it piped incorrectly. You might want to double check that.

    Your "supply to the heat source" and your "hot outlet" are mixed up." The thermostatic mixing valve hot input is connected to where the boiler supply is suppose to be connected. There is no reason that the boiler supply to the tank and the boiler return
    from the tank have to go to the ceiling.

  • rick in Alaskarick in Alaska Member Posts: 1,149
    Close the valve above the circulator and open up the drain valve above it and flow enough water to make sure there is no air.
    Sounds like you are definitely not getting enough flow to even make your boiler pull down very much. You might even want to take the pump apart to make sure it isn't restricted. No offense, but there is a lot of solder and pipe dope floating around there, and it might have got in to the pump.
  • ZmanZman Member Posts: 6,318
    The boiler cycling is the big clue. The heat is not being transferred. The coil in the indirect appears to be big enough.
    The delta t (temperature difference) between the supply and return temp is a big clue. As Mark noted, if there is no check valve on the heating circ, that could be the problem.

    You will be surprised how much information can be a attained by simply feeling the pipes.

    If everything has been thoroughly checked, for the normal issues, it is time to start looking for the weird stuff.
    Clock the gas meter, check for junk the factory or plumber left in the pipes....

    This system should outperform the old one. You just have to figure out what is wrong.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • SeymourCatesSeymourCates Member Posts: 162

    I do believe you are onto the problem with the use of 3/4" and the cycling of the boiler when making DHW.

    Take a look at the last photo. If my old eyes do not deceive me, the supply is the iron pipe at the rear of the boiler. Follow it up and it changes to copper after the air separator.

    Then, you can barely make out a set of what appears to be 1" x 1" x 3/4" tees. If one of the 3/4" lines feeds the indirect, that would pinpoint the problem.

    Need better photos of the piping between the boiler and the indirect.
  • HomerJSmithHomerJSmith Member Posts: 1,103
    From the Heat-Flo manual. Tank connections!


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