Burnham series 2 Heat exchanger

Discussion in 'Boiler Forum' started by Heyjoe, Feb 17, 2020.

  1. Heyjoe

    Heyjoe Member

    Joined:
    Feb 17, 2020
    Location:
    Colorado
    Hi, I have been searching for answers and stumbled on this forum.

    I have a question regarding a Burnham series 2a hydronic boiler that is 25 years old. The boiler pressure goes from 12 psi cold to 25 hot and sometimes during the cycle it climbs just over 30psi causing a small amount of water to be released. The expansion tank is new and preset at 12 psi. The 30 psi relief valve is new and the pressure reducing valve is set at 12-15 also new.

    I do have a boiler mate / water heater and there is no leak in the heating coils inside. The two system pumps,taco 007 and 0011 are working.Can the boiler heat exchanger be the problem? Will a clogged water tube or tubes in the boiler cause this pressure increase?Can a build up of soot in the flue passageways in the boiler cause the problem? Can it be a sign that a heating zone in the floor is getting clogged. I flushed the boiler and the water was clear.
     
    Last edited: Mar 12, 2020
  2. Dana

    Dana In the trades

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    Location:
    01609
    If the expansion tank was sized correctly and pre-charged correctly the system pressure should never hit 30 psi.

    Is the system pressure creeping up over time, or only when firing? Does it always drop back to 12 psi when cool after a cycle that hits 25 psi?

    If heat exchanger has a pinhole leak, the pressure on the system will creep up over time.

    No. (And not that it matter, the Series 2 are not water tube boilers- they're cast iron plate type boilers.)

    No.

    QUOTE="Heyjoe, post: 616314, member: 94553"]
    Can it be a sign that a heating zone in the floor is getting clogged. I have entran 3 hose under the floor can that hose be flushed and cleaned with some product. I flushed the boiler and the water was clear.[/QUOTE]

    It has nothing to do with the EPDM tubing, even if it happened to be the case that the tubing was failing.

    The things that cause pressure to rise over time (not temperature) are seepage at the pressure reducging valve, or leaks from the heat exchanger inside the water heater. If either of those is the problem, with isolaing valves it's possible to sort out which is the culprit.

    The things that cause excessive pressure rise with temperature are undersized expansion tank, or improperly charged expansion tank. To deal with that:

    Try pumping air into the tank until the air pressure reads 15-20 psi. The water pressure on the system should rise accordingly. Bleed the water pressure back down to 12 psi, then test the air pressure with a tire gauge. If it's 12 psi, pump it back up to 15-20 psi. If the system pressure doesn't change, bleed the air back down to 15 psi. If the system pressure rises, bleed water out of the system until it hits 12 psi. Repeat. When pumping air into the tank no longer changes the system pressure, it will have the maximum possible expansion room- so bleed air until the air pressure down to about 1-2 psi above the (cold) system pressure.
     
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  4. Heyjoe

    Heyjoe Member

    Joined:
    Feb 17, 2020
    Location:
    Colorado
    It has nothing to do with the EPDM tubing, even if it happened to be the case that the tubing was failing.

    The things that cause pressure to rise over time (not temperature) are seepage at the pressure reducging valve, or leaks from the heat exchanger inside the water heater. If either of those is the problem, with isolaing valves it's possible to sort out which is the culprit.

    The things that cause excessive pressure rise with temperature are undersized expansion tank, or improperly charged expansion tank. To deal with that:

    Try pumping air into the tank until the air pressure reads 15-20 psi. The water pressure on the system should rise accordingly. Bleed the water pressure back down to 12 psi, then test the air pressure with a tire gauge. If it's 12 psi, pump it back up to 15-20 psi. If the system pressure doesn't change, bleed the air back down to 15 psi. If the system pressure rises, bleed water out of the system until it hits 12 psi. Repeat. When pumping air into the tank no longer changes the system pressure, it will have the maximum possible expansion room- so bleed air until the air pressure down to about 1-2 psi above the (cold) system pressure.[/QUOTE]
    It has nothing to do with the EPDM tubing, even if it happened to be the case that the tubing was failing.

    The things that cause pressure to rise over time (not temperature) are seepage at the pressure reducging valve, or leaks from the heat exchanger inside the water heater. If either of those is the problem, with isolaing valves it's possible to sort out which is the culprit.

    The things that cause excessive pressure rise with temperature are undersized expansion tank, or improperly charged expansion tank. To deal with that:

    Try pumping air into the tank until the air pressure reads 15-20 psi. The water pressure on the system should rise accordingly. Bleed the water pressure back down to 12 psi, then test the air pressure with a tire gauge. If it's 12 psi, pump it back up to 15-20 psi. If the system pressure doesn't change, bleed the air back down to 15 psi. If the system pressure rises, bleed water out of the system until it hits 12 psi. Repeat. When pumping air into the tank no longer changes the system pressure, it will have the maximum possible expansion room- so bleed air until the air pressure down to about 1-2 psi above the (cold) system pressure.[/QUOTE]
     
    Last edited: Feb 19, 2020
  5. Heyjoe

    Heyjoe Member

    Joined:
    Feb 17, 2020
    Location:
    Colorado
    Thanks the pressure gradually creeps only when firing and goes down when off. I will check the tank pressure and increase it like you mentioned. I will also isolate the boilermate and pressure reducing valve if the tank method doesn’t solve the problem.
     
  6. fitter30

    fitter30 Member

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    Occupation:
    Retired service tech
    Location:
    Peace valley missouri
    Is the expansion tank has to piped on the suction side of the boiler pump to work properly also out of the air charge valve is there any water coming out when depressing it? Soot won't raise water pressure and i would wait on putting cleaner in this system since water from boiler drain is clear.
     
    Last edited: Feb 19, 2020
  7. Dana

    Dana In the trades

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    Location:
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    If the pressure always drops back to the same pressure when the system cools off, it's all about the expansion tank size & charging levels.

    The pressure reducing valve & boilermate would only be worth checking if the pressure measured when the system was cool or tepid kept creeping up.
     
  8. Heyjoe

    Heyjoe Member

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    Feb 17, 2020
    Location:
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    I started having second thoughts about putting any chemicals in the system.The last thing I need is to start dissolving the hose.

    Dana, pretty much convinced me the hose was not the issue. I am going to look at the expansion tank, but since it’s new I am also making a list of the “usual suspects.”

    I reached over and grabbed the pipe supplying the tank and realized it was not getting hot. I thought I had found the problem. In my mind I was assuming that as you heat water the volume of water increases and that extra “hot”water volume would flow into the tank, I wasn’t really thinking in terms of vapor pressure, like a tea pot. But,when I removed the tank there was obviously water in it and my plumber said there wouldn’t be any water and that’s why the the tank doesn’t heat up. I have a problem with his way of thinking, but the tank doesn’t heat up.

    The air eliminator is starting to appear as a good candidate, in my “non -plumbing mind” it seems to be a vital part of the expansion tank operation.


     
    Last edited: Feb 25, 2020
  9. Heyjoe

    Heyjoe Member

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    Thanks for your help. By directing my attention to the “new”tank I found that it wasn’t getting hot.Now it looks as if the air eliminator is somehow not allowing water or “vapor pressure “to pass in to the tank. Thanks again, I am glad I found this forum.
     
    Last edited: Feb 25, 2020
  10. Heyjoe

    Heyjoe Member

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    I thought I found the problem, now I see that the pipe to the tank won’t get hot except for the first foot or so. below the air eliminator. Now the pressure testing on the tank, them on to the air eliminator and on to pressure reducer and checking the pumps for foreign material.

    This size expansion tank has been on the system for 25 years,but when I looked at amtrol’s site their calculator said it should be a #60 not a #30. They might be right but I don’t think that’s the problem. It’s easy to change and will do it and keep the 30# for a spare.
     
    Last edited: Feb 25, 2020
  11. Heyjoe

    Heyjoe Member

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  12. Heyjoe

    Heyjoe Member

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    Feb 17, 2020
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    The expansion tank is set at 12. No water comes out the schrader valve when pressed and tapping on the tank side high sounds dull at the top and tiny lower on the sideand low side.


    I can isolate the pressure reducing valve and the boilermate water heater and no water seems to be getting drawn into the system. The pressure. rises to 20 to 30 psi.drops to 15 to 25 during off cycles. When the system shuts down the pressure drops to about 10.

    Not sure of the accuracy of the gauge but it is probably is + or - a few psi. I question the accuracy because the boiler tridicator gauge doesn’t coincide with the pressure reducing valve setting.The pressure relief valve is new set at 30psi and it’s obviously working pretty close to that pressure.The temperature side of the boiler gauge and the high limit setting are close.

    The expansion tank is new and it’s the same size #30 that has been on the system for years with no pressure problems. The system circulator and return pumps work.The only thing I am not sure if is the air eliminator, but from what I’ve read it can’t cause increases in pressure.Is the boiler ready for the scrape yard?
     
    Last edited: Feb 25, 2020
  13. Dana

    Dana In the trades

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    If the tank's pressure is still measuring 12 psi when the system pressure it 15- 25 psi the pipe to the tank is blocked. Is there an isolating ball valve between the tank and the rest of the system?

    A picture of the air scoop & tank might be useful here.
     
  14. fitter30

    fitter30 Member

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    Occupation:
    Retired service tech
    Location:
    Peace valley missouri
    Bladder tanks are usually sized 1% of total total system volume. Unless you have a very large house 30 gallon tank should be good for 300 gallons. Like dana wrote take some pics.
     
  15. Heyjoe

    Heyjoe Member

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    Feb 17, 2020
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    Colorado
    The tank pressure 12 psi cold. It’s a #30 amtrol tank, 4,4 gal. No isolating valve.It seems like there should be one to make changing tanks easier. The air eliminator is a spirovent. The spirovent has never been cleaned. I am going to find out if I can buy a kit for it before I take it apart. When I used an on line calculator it said my expansion tank should be #60,based on 198000 btu boiler, but for 25 years it’s has had the #30.I will put on #60 tank.
     
    Last edited: Mar 12, 2020
  16. Heyjoe

    Heyjoe Member

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    I am guessing that I have about 2000 feet of 3/8 tubing and 600 feet of 3/4 copper pipe.That calculates to about 24 gallons 1% equals ..24 gals.The house is 3000 sq ft. The upper 2000 sq ft has 5 zones of in floor tubing and the 1000 sq ft in the basement is heated with baseboard. Baseboard heaters totaling 30ft.

    PS the plumbing house salesman sized the Burnham series 2 198000 btu boiler.After the first year in the house I told him I thought it was too large.He said he sized it so that I could add on to the house.
     
    Last edited: Feb 24, 2020
  17. Dana

    Dana In the trades

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    That would be the 7 plate 207, which has a DOE output of 163,000 BTU/hr, enough heat to keep my sub-code 2400' house + 1600' of insulated basement warm at -200F outside.

    Even derated for altitude that's a LUDICROUS sized boiler for a 3000 square foot house and would have a reasonable oversize factor even if you doubled it to a 6000' house (unless you were planning on skipping the glass in some of the windows or something.) Even derated for Leadville's 10K' it would be good for over 115,000 BTU/hr of DOE output. (115,000 /6000 sq.ft. = 19 BTU/hr per square foot- a code-minimum R addition should have load per square foot closer to 15 BTU/hr per square foot @ Leadville's -14F outdoor design temp).

    Since you have a heating history on the place, run a fuel-use based load calculation on the existing house when contemplating boiler replacements. Bear in mind that a current code min-addition on an older house can even LOWER the total heat load, if it's replacing an air leaky 2x4/R13 0r 2x6R19 type wall with clear glass double panes with a 50% greater amount of 2x6/R20+ R5 c.i. & U0.30 or lower low-E window.
     
  18. Heyjoe

    Heyjoe Member

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    The tank is on the supply side. Water comes out of the boiler then the PRV valve is piped in then the air eliminator is in-line and the tank is plumbed on the pipe coming out of the air eliminator bottom after the eliminator the supply water goes into the boilermate zone then to the zone for the basement’s baseboard heaters then a manual py-pass comes in from the return side then the supply goes into a circulation pump and then into the five radiant floor zones.

    I plan on getting rid of the manual by- pass and install a mixing valve before I die.The manual by-pass does not lower the temperature enough for the floor. When the boiler gets 160 + degrees the closet floor zone reads 150. The return water is 125. So, even though the entran engineer said the hose was tested to 200 degrees. Once I learned of their past record I had no reason to trust them.So I run the boiler at 140 degrees, the baseboard and the water- heater lack some heating, but the thought of damaging 2000’ of hose that is not easy to get to isn’t worth the benefits. The floor seems to require 135 to 140 degrees. Since there is only two of us hot water is not an issue. The basement does ok, but it does work better at 180 degrees.The hose is a staple up, with 3|4 inch plywood. Plywood seems to be a fairly good insulator, so the 120 degree water temperature number they kept throwing out sounded pretty good. When I was planning the floor layouts, they seem to have “forgotten” to bring up the heat loss in the sub floor.I didn’t catch it until latter.

     
    Last edited: Feb 22, 2020
  19. Heyjoe

    Heyjoe Member

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    I later learned that the local Fergusons was notorious for over-sizing boilers.Two of my friends were building homes about the same time and were sold the same boiler. We should have done the math instead of relying on someone else.

    When I get the boiler pressure problem figured out I was, just out of curiosity, going to see how many seconds it took to use a cubic foot of natural gas and do the math The boiler tag has the second number at 161,000btu I assumed that is where boiler efficiency comes in. 81.5 % for the series 2. I am at 5000 ft. altitude. In the event I replace the boiler I was guessing 135 to 140000 btu. When I use the 50 btu per sq.foot I get 150000btu.
     
    Last edited: Feb 21, 2020
  20. Dana

    Dana In the trades

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    At 5000' you would only need to derate to 85-90% of the labeled DOE output, maybe less (depending on where Burnham's literature starts the derating.)

    Seeing how many minutes it takes to burn through a cubic foot of gas isn't going to tell you anything about your heat load. My understanding is that many local gas-grids in Colorado adjust the mixture of gases in the fuel to a somewhat lower BTU content so that equipment designed for lower altitudes will always work without modifying the equipment, which may be where the 161K label came from(?).


    Why on EARTH would you use something as ridiculous as "...50 btu per sq.foot..."?

    What is your local 99% outside design temp (approximately)? Most locations in CO at or near 5000' have design temps in low to mid positive single digits F. But to keep it simple let's assume 0F, a design temp where I have more experience.

    A typical tight 2x4 framed insulated house with clear glass double-panes would come in under 20 BTU/hr per foot @ 0F outside many would be around 15 BTU/hr per foot.

    A tight 2x6/R20 house without insulating sheathing would come in around 10-12 BTU/hr per foot @ 0F.

    Bigger houses usually have more efficient shapes, and lower BTU/ft^2 ratios.

    Is this a completely UN-insulated house with steel sash single panes or something?

    All BTU per square foot rules of thumb suck, and cannot be used for accurately sizing the equipment, but some rules of thumb suck worse than others. 50 BTU per square foot is almost guaranteed to come in 3x or more oversized. While ludicrous oversizing factors don't hurt efficiency for hot air furnaces (it only hurts comfort) it's a significant efficiency hit for a cast iron boiler.

    ASHRAE recommends sizing the boiler output to 1.4x the load at the 99% outside design temp, so if it's a 2x6/R20 type 3000' house the design load is likely to be around (or less than) 48,000 BTU/hr @ 0F, and the "right sized" boiler for the heat load would have an output of 1.4 x 48,000 BTU/hr= 67,200 BTU/hr. At 82% efficiency that would be an input of about 82,000 BTU/hr, so in the Burnham Series 2 lineup you'd be looking at the 204 (DOE output of 96K at sea level or about 82-85K derated for altitude.)

    Correlating fuel use to heating degree days is a pretty good model for estimating heat loads. It's not perfect, but it's a measurement (however crude), and way better than a rule of thumb!
     
  21. Heyjoe

    Heyjoe Member

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    Feb 17, 2020
    Location:
    Colorado

    It has nothing to do with the EPDM tubing, even if it happened to be the case that the tubing was failing.

    The things that cause pressure to rise over time (not temperature) are seepage at the pressure reducging valve, or leaks from the heat exchanger inside the water heater. If either of those is the problem, with isolaing valves it's possible to sort out which is the culprit.

    The things that cause excessive pressure rise with temperature are undersized expansion tank, or improperly charged expansion tank. To deal with that:

    Try pumping air into the tank until the air pressure reads 15-20 psi. The water pressure on the system should rise accordingly. Bleed the water pressure back down to 12 psi, then test the air pressure with a tire gauge. If it's 12 psi, pump it back up to 15-20 psi. If the system pressure doesn't change, bleed the air back down to 15 psi. If the system pressure rises, bleed water out of the system until it hits 12 psi. Repeat. When pumping air into the tank no longer changes the system pressure, it will have the maximum possible expansion room- so bleed air until the air pressure down to about 1-2 psi above the (cold) system pressure.[/QUOTE][/QUOTE]
     
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