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Who ya gonna call?

WandaMaximoff Member Posts: 1
edited February 2021 in Domestic Hot Water
I recently moved into a house that my partner has owned for a while now, and I just found out this winter that there’s a major issue here with the domestic hot water not coming out hot enough/lukewarm. The house uses oil heat and has an old boiler with a domestic water coil that at this point talking with some different HVAC people we think that most likely the coil and mixing valve need to be replaced. The boiler heats the house well and is not having other issues, but the boiler is so old that locating replacement parts is proving extremely challenging (might not be possible). The first thoughts we had about the water heat were “oh, we should just get a water heater installed”. We don’t have the electrical or anything hooked up for that right now. One company came out and quoted us $xxxx for the 50 gallon water heater and to install it but said they don’t do electrical and you need to call someone else for that. Another company came out and quoted us a totally different price for the entire project on a 40 gallon water heater to install it and hook up the electrical. A third person also estimated on the phone using pictures and questions an approximate cost of $xxxxx (somewhere in between both estimates) for the 50 gallon water heater hook up and said they would have to come out to give an electrical estimate. 

The current boiler is a one zone 139100 BTU Rating. I got two totally different estimates.

Realistically speaking our budget is really maxed out at $4,500-$5,000, but we could stretch, tap dance, etc. to probably finance or borrow up to $7,000 if the best option really would be to just replace the boiler. 

At this point though I’m utterly lost with if we should be calling a plumber, HVAC, giant Corporation, etc. and what is the most cost effective solution.


  • Jamie Hall
    Jamie Hall Member Posts: 22,972
    Well... the first thing to do is to edit out the pricing. We don't quote pricing on the Wall -- we don't have many rules, but that's one of them.

    OK. So much for that.

    The heating coil in the boiler may not need replacing, never mind the boiler, so before you go off the deep end on this, try de-scaling it. There are some proprietary products for that, but as a first try at it figure out how to get simple white vinegar in there with about 50/50 water and, i possible circulate that for a few hours -- if you can't circulate it, just let it sit overnight. You mention a mixing valve, too, and it is equally possible that it too is gummed up. Same treatment.

    I the worst is true, and you have to add a water heater, I would humbly remind you -- and your contractors --that there are such things as oil fired hot water heaters, which work far better, size for size and dollar for dollar, than the electric sort. Since you already have oil heat, it would be a matter of locating a place for its exhaust flue. I might mention that both of the residences I currently care for use 32 gallon oil fired hot water heaters; one normally has 5 people living there, the other can have as many as 10 -- and I've yet to hear a complaint about not enough hot water.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    WandaMaximoffSuperTechErin Holohan Haskell
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 7,618
    edited February 2021
    Agree with all of what @Jamie Hall said but would like to add that the temperature settings on the boiler controls may need to be adjusted. As old as the heater is and not having the tankless coil maintained, there is most likely some build-up inside there that is reducing the heat transfer from the boiler to the potable water. Adding more temperature to the boiler water may get you temporary relief.

    Depending on the control configuration your operating limit or low limit should be set at a minimum of 160°F with a small differential (if that is adjustable) The high limit should be set at least 20° higher than the low or operating limit. That would be 180° If your system is really old and you have a separate Reverse for the circulator, then that should be set at 155° Don't worry about that if your boiler has a triple aquastat relay like this
    Set the Low at 160 Hi at 180 and diff at 10.
    If they are already there then bump up the low to 170 the high to 190 and leave the diff at 10
    The highest i would set is 180 low 200 high and 10 diff.

    Check those settings first and look at the temperature gauge of the boiler to see what the actual temperatures are when the boiler is operating for hot water.

    Just realize the higher the temperature settings are, the more fuel you will use, so those higher settings are temporary until you have time to pick your best option.
    Edward F Young. Retired HVAC ContractorSpecialized in Residential Oil Burner and Hydronics
    EBEBRATT-Ed Member Posts: 15,353

    A tankless heater coil is not "top of the line" for providing a supply of hot water. But, many people in a small household get by fine with them for a couple of people.

    So one option is to locate a replacement tankless coil. Everhot (in the Boston area) makes replacement tankless coils for most boilers. But, before you go this route you have to have a pretty good idea if the bolts securing the coil will come out. They can get rusted in. Use a good mixing valve with this

    You didn't mention if the boiler is hot water or steam?

    Electric water heater is an option depending on whatt you have for an electric service. If you have an electric dryer, range, large air conditioner etc then you may need a 200 amp service. If your not that heavy with electric appliances you may be ok on a 100 amp service. No chimney needed

    Oil fired water heaters are $$$ Has to be flued into the same chimney as your boiler (is it large enough) and gives you another burner to maintain.

    If you have LP gas available that would be a good option. (I assume you dont have natural gas since you are on oil.

    And lastly an indirect water heater is a seperate hot water tank that is heated by your exisyting boiler.
    This could be retained and used if you replace the boiler in the future


    Lots of choices. The best choice is determined by the fuel(s) you have available, your budget and how much hot water you need, # of family members etc
  • WandaMaximoff
    WandaMaximoff Member Posts: 1
    We don’t have natural gas here at all.

    The boiler is hot water (not steam).

    and right now we’re talking about hot water for 3 people. 

    Thanks for the information! 
  • SuperTech
    SuperTech Member Posts: 2,127
    The quality of your water has to be considered as well.  If you have hard water the coil will need more frequent descaling. A tank might be a better option.  In my area customers prefer tank type water heaters, indirect or direct fired.  A Bock 32E oil fired water heater will outlast just about any electric water heater.  
  • psb75
    psb75 Member Posts: 812
    If you are considering an electric water heater, you should definitely put in a 50 gal. heat pump water heater. Check for the possibility of rebates, tax incentives--they are quite good in some regions. You will need a dedicated 30 amp, 220vac circuit from your main panel. There is also a 65 gal. option for not much more money. These are very economical to run. Better than a regular electric water heater.
  • Condoman
    Condoman Member Posts: 91
    When we moved into our home the hot water boiler was under 5 years old. The coil was not doing the job. On inspection the service company corrected the settings and it worked OK. We seemed to lack quantity after that. Next we installed an indirect (MS-40) after verifying the water Ph was suitable. No problem for 8 years since then. The coil is drained and dormant. Just FYI if that helps.
  • WandaMaximoff
    WandaMaximoff Member Posts: 1
    After talking with one of the contractors who has been the most helpful we found out our boiler is from the 60’s. 😮 It’s still working for us, but the coil is actually not a removeable part in this boiler. We’ve decided to go with installing an electric tank water heater.