hot water

Discussion in 'HVAC Heating & Cooling' started by Barry J, Mar 2, 2007.

  1. Barry J

    Barry J New Member

    Messages:
    99
    Location:
    Mass
    I have a Weil-McLain Oil Burner and had the yearly maintainence done on it 4-6 weeks ago. The guy said the boiler looks great and real clean. I was down their pretty much the whole time he was here. That night I noticed the heat would not come on. It would run for hot water but not for heat. I called them (9pm on friday night). They came out and replace the control. A Honeywell L8124 aquastat. Since then, when we run the bath or shower, we have to keep on adjusting the water hotter, to keep the heat up. And after a while it turns luke warm. I turned the mixing value up, only a little,but that was no help. It's acting like the coil is going, but we replaced that a couple of years ago. My aquastat is set at High=205, low=180 and differential on about 16. Any suggestions
    Thanks
    Barry
  2. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    21,824
    Location:
    New England
    I was talking to a tech recently, and he said he had similar problems. Took him a long time to figure it out, but the thermocouple had been dislodged slightly and was not sensing the system temperature properly. ALl he had to do was reseat it, and it worked fine. Might be something as simple as this. You can often find the specs on the thermocouple in the aquastat. It has a predictable resistance based on temperature. You can check it to verify the accuracy, and, to see what temperature it thinks it is seeing.
  3. Barry J

    Barry J New Member

    Messages:
    99
    Location:
    Mass
    where is the thermocople and how do
    I reseat it?? Is it the tubular-looking thing that was attached to the aquastat??
  4. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    21,824
    Location:
    New England
    The thermocouple is an essential part of an aquastat, so I'd say, yes. An aquastat is a specific type of thermocouple, designed to sense the temp of water. It might have extra functions, like a built-in switch(s).
  5. Barry J

    Barry J New Member

    Messages:
    99
    Location:
    Mass
    like I said the aquastat is brand new, I guess I should contact the company and inform them they installed a "lemon"
  6. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    21,824
    Location:
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    It's hard to say...I would call them back and tell them the symptoms.
  7. coz

    coz New Member

    Messages:
    91
    Location:
    MA
    what does the temp of your boiler read? if its hot enough , its probably your mixing valve. If you buy the same brand you can change the guts in mins. worth a shot.
  8. Barry J

    Barry J New Member

    Messages:
    99
    Location:
    Mass
    The temp. on my boiler is reading about 145 degrees. I'm going over to my dad's house today to see what is aqustat is set for Highs/lows/diffs
  9. coz

    coz New Member

    Messages:
    91
    Location:
    MA
    thats too low go 180/200 20 differential
    you can turn up the aquastat higher just use the gauge on the boiler to get the temp right. the aquastats aren`t always spot on. cycle the boiler a few times and watch the gauge to see if its coming on at 180 and shutting off at 200.
  10. Barry J

    Barry J New Member

    Messages:
    99
    Location:
    Mass
    Being low...would that be why I'm running out of hot water??
  11. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    21,824
    Location:
    New England
    The heating coil is probably rated for a minimum of 180-degrees, so if it is down to 145, then yes, you will not get much hot water. Actually, you'll get probably as much warm water as you want, but since it is going through 145-degrees rather than 180, it just can't pick up as much as previously.
  12. Bob NH

    Bob NH In the Trades

    Messages:
    3,317
    Location:
    New Hampshire
    I had a problem with the tempering valve which is near but not part of the furnace. It mixes cold water with hot to keep the hot water delivered to the system at a "constant" non-scalding temperature. It was letting in more cold water than it should. I ended up taking the stem out of mine which disabled the mixing without the need to change the plumbing.

    The problem occurred when the supply water got to about 34 F in the winter.

    A few years ago I put a 40 gallon electric on the outlet side of the tankless in my boiler, with the electric setting below the tankless discharge temperature. In the wintertime, the electric never comes on and my water temperature is very stable. In the summer, I shut off the boiler and save more than enough $2.30 per gallon oil to pay for the electric water heating for two people. Keeping a boiler hot for hot water in the non-heating season burns a lot of oil to supply warm air going up the flue.
  13. Barry J

    Barry J New Member

    Messages:
    99
    Location:
    Mass
    Ok, just got off the phone with the owner of the oil company that services my furnace. His suggestions were to keep my high at 205, and turn my low to 195, and switch my differential to about 10. He thinks the water is going too fast thru my coil and not heating enough. Also, he said to turn up the mixing valve, ...I did all of this, but the mixing valve is already up to max. Also, I mentioned the tank temp gauge was on 145 degrees, but when I went down to make these changes it was at 180 degrees, must have just ran for hot water. Any feedback on his suggestions??
    Also, he suggested in the future because of my four person family, that I might think of a water tank, but, he said it is pretty expensive (around $1,300) but mentioned that could be in the future, not needed now.
  14. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    21,824
    Location:
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    I lived with a situation similar to yours, and I ended up (just this January) putting in an indirect water heater. This is basically plumbed in as a separate (often a priority) zone of the boiler. There is a coil in it to heat the stored water, so there is a good supply of hot water, just like a stand alone gas, oil or electric water, but it gets its heat from the boiler. The better ones have standby losses in the order of 1/4-degree/hour, so unless using hot water, they keep what you've got for a long time. They come in various sizes and internal finishes (I got a stainless steel lined tank). Because they have the full output of the boiler (if on a priority zone), they heat faster and (typically) a smaller tank is sufficient than if it was a stand-alone unit.

    While keeping the boiler at that (fairly high) temperature, you will be wasting a lot of fuel and it will cycle more. It should help the hot water supply, though. The better long-term solution would be a different way to heat the water. Bob's solution works, but watch your utility rates. Electric can be expensive in many areas, more so than oil sometimes.

    Note, most of the newer, high-efficiency boilers have verly little internal capacity, and keeping one hot isn't too expensive. Not sure if this is done with oil-fired jobs, though, but is fairly common for gas.
  15. coz

    coz New Member

    Messages:
    91
    Location:
    MA
    had one plumber tell my customer(now) his coil was failing and sold him on an indirect water heater. I changed the guts in the mixing valve. endless hot water.That was 2 years ago still running strong.
  16. Bob NH

    Bob NH In the Trades

    Messages:
    3,317
    Location:
    New Hampshire
    Take the little rod out of the tempering valve and see what happens. You can usually do that by turning off the water and removing the part where the adjustment is located. That, plus cranking up the temperature setting, should solve the problem.

    I really like my "second stage" electric (see my earlier post on 3/7 on this thread). I did the plumbing and electric myself so it only cost about $60 more than the price of the water heater at HD. It uses no electricity in the winter, and in the summer the electricity costs less than it costs to keep the boiler hot with expensive oil.
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