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HTP Hot plastic odors

mattmia2mattmia2 Posts: 13Member
I have a UFT-100 boiler installed with an SSU-40 indirect water heater with a Caleffi air separator and a Grundfos Alpha II pump(and pressure reducing valve and expansion tank and other assorted accessories for a complete system). The flow calculations show about 4 gpm and the pump reads 3 gpm. It intentionally has a lower flow to keep the return water temp in the condensing range most of the time. The DHW heating supply is set to 135 degrees and the DHW firing rate is set to 65%. It is using the HTP indirect tank probe and is set to 118 degrees with a 5 degree delta T. A combustion analyzer shows about 8.8% carbon dioxide and no carbon monoxide at low fire. It was running rich for about a month before adjustment. It also was shipped via UPS so it was likely dropped.

I experience a hot plastic or rubber smell that I think is coming from the foam insulation around the boiler vessel in the area above the water line. That area seems to not exceed 190 degrees or so but it is difficult to accurately measure the temperature of a surface like that(this was measured when the mixture was rich and it seemed the smell was worse with the rich mixture). It seems to happen more at the end of a DHW call as the tank approaches the setpoint and delta T of the boiler water falls. If you increase the boiler setpoint to 145 degrees there is significantly more of the smell. It has been running for about 2 months with only the DHW load so it should have had time to remove any manufacturing residues. It is set up in a powered vent configuration and is installed with the included cpvc nipple on the exhaust (but the smell does not appear to be coming from the intake).

Has anyone seen anything like this? The boiler should be operating in its modulating range. I am wondering if there was a material that didn't meet spec used for the boiler insulation. It also seems that 1/8 of foam has so little insulating value that it is pointless anyhow. Is there some component behind the boiler vessel that might be making the smell?

It is planned to also heat some zones of baseboard in my basement but that has not been installed yet.

Comments

  • EBEBRATT-EdEBEBRATT-Ed Posts: 5,804Member
    Don't know. Maybe run the temp up high for a while and set it back down see if it cooks off
  • HenryHenry Posts: 899Member
    Keeping DHW at 118F is extremely dangerous for the propagation of bacteria and legionella! Storage tanks must be kept at 140F for human safety. Let the boiler operate the way it was designed to do: normally at least 20F over 140F tank temperature.
  • mattmia2mattmia2 Posts: 13Member
    Why is that dangerous? Virtually no domestic hot water tank is set over about 130. The water is treated at the utility with disinfectant, it still has residual disinfectant in the tank and the volume of the tank is replaced in about a day.

    BTW, do you have an answer to my question?
  • mattmia2mattmia2 Posts: 13Member
    Running a system at that high a temp loses many of the advantages of using a condensing boiler and an indirect. Condensing boiler systems have to be engineered to run at system water temps under 130 degrees to keep the boiler condensing.
  • mattmia2mattmia2 Posts: 13Member
    This is a separate boiler and indirect tank, the system and domestic water do not mix. If this were an issue in this application people would be getting sick from their conventional gas and electric water heaters. My water is disinfected with chloramine, i'm not sure how stable that is with heat but I know it is difficult to remove for aquariums.

    The rise will depend on the transfer rate of the coil in the indirect and how much the cold water and hot water mix in the tank.

    I have submitted the same question to HTP.
  • nmac86nmac86 Posts: 5Member
    I had the same smell on my HTP UFTC-140. The smell is definitely coming from the insulation around the boiler vessel. It did go away but took at least a month, maybe 6 weeks.
  • Wait and see what HTP says.

    Your system is new and it may take awhile to burn off any residual processing chemicals. I'm often alarmed at some of the odors that come from a new installation. It's that "new boiler" smell.

    Is this a system you installed? If not, find out who did the work and ask them to figure it out. If yes, check your work and make sure you didn't do something wrong.

    I find that 90% (or more) of problems stem from installer errors.
    Often wrong, never in doubt.

    Click here to learn more about this contractor.
  • mattmia2mattmia2 Posts: 13Member
    It is interesting that you say it took 4-6 weeks for the smell to go away. Since it is currently only serving the DHW load which is SSU-45 and i live alone it only fores 2-3 times a day. If you have heating loads on it (it will eventually intermittently heat my basement workshop and garage) it might take months for me to get the equivalent of a month of run time serving heating loads.

    At EBEBRATT-Ed's suggestion I set the boiler dhw call setpoint at 180 and the smell diminished immediately, on the first call there was barely any smell escaping the cabinet. I doubt it ever got to the setpoint before satisfying the dhw call but either the shorter cycle or the higher fan speed made whatever was getting hot not get as hot.

    HTP asked me to open up the combustion chamber and take pictures. Nothing looked unusual to me but I'm not sure what they are looking for.

    As a side note, the way everything is pressurized through the system and has many sealing surfaces is scary. There are so many places that an air leak could result in a gas leak, very hot combustion products leaking or cooler combustion products leaking and I don't really see any way the controls would detect this in most cases.

    Thanks for your help.
  • CanuckerCanucker Posts: 532Member
    > @mattmia2 said:
    > This is a separate boiler and indirect tank, the system and domestic water do not mix. If this were an issue in this application people would be getting sick from their conventional gas and electric water heaters. My water is disinfected with chloramine, i'm not sure how stable that is with heat but I know it is difficult to remove for aquariums.
    >
    > The rise will depend on the transfer rate of the coil in the indirect and how much the cold water and hot water mix in the tank.
    >
    > I have submitted the same question to HTP.

    People do get sick from their conventional gas and electric water heaters. The most at risk are the very young, the elderly and people with depressed immune response. It is also notoriously difficult to diagnose. Any of those groups breathe in the blooms from a tank kept between 93-116 F could get very ill and die.(Think aerators and showers) The amount of chlorine necessary to kill it would render the water unfit for consumption, which is why it is recommended that the tanks see 140F+ to sanitise the water. Recommending the tanks be kept at 120 or less to save energy is irresponsible, in my opinion.
    You can have it good, fast or cheap. Pick two
  • delta Tdelta T Posts: 750Member
    As to the Legionella risk, the break down is as follows (from wikipedia based on a WHO report linked below)

    158 degrees and up bacteria die almost instantaneously
    140 degrees, 90% die in 2 minutes
    122 degrees, 90% die in 80-120 minutes (depending on specific strain)
    118 degrees, none die, but generally do not multiply
    90-108 degrees is the ideal growth range.

    more info here:

    https://www.who.int/water_sanitation_health/emerging/legionella.pdf

    Chapter 2 talks about the temperature ranges.

    The reason most people don't get sick, is that most DHW tanks are set at about 125 or so. This is the minimum level at which most leigionella will be killed (if given enough time, usually hours), however, a much safer and more effective temperature is 140. With a good quality, well-insulated tank, and a good mixing valve on the outlet of the tank, there is very little difference in energy use storing at 140 vs 125 for the average residential boiler driven DHW system. The other advantage of storing at a higher temp is that you end up with more available hot water than you would otherwise have.
  • mattmia2mattmia2 Posts: 13Member
    so between overshoot and it being a storage tank, 118 will kill legionella

    btw, i might agree with you to some extent, but that wasn't my question and this is a controversial subject, so if you would like to debate it start your own thread with that subject
  • mattmia2mattmia2 Posts: 13Member
    If it is a condensing boiler there is about a 10% difference in energy use between about 120 and 140 because the boiler won't be taking most of the heat of vaporization out of the fuel burned in the boiler.
  • flat_twinflat_twin Posts: 203Member
    The fact that legionella dies quickly at 140 isn't controversial at all. I have never seen a thread or post here or on other boards where a tradesman recommended operating an indirect in the temperature range you're suggesting.
    For space heating, yes it's important to design the system to operate in the condensing range but not for making dhw.
    Our indirect dhw cycle is 10-12 minutes, two or three times a day. You're chasing tiny gains at the risk of harboring legionella.
  • CanuckerCanucker Posts: 532Member
    > @mattmia2 said:
    > If it is a condensing boiler there is about a 10% difference in energy use between about 120 and 140 because the boiler won't be taking most of the heat of vaporization out of the fuel burned in the boiler.

    Making DHW tends to be a small percentage of your overall fuel use compared to the time spent heating the structure. I don't believe it is a full 10% drop during the priority call, just the tail end of it. YMMV.
    You can have it good, fast or cheap. Pick two
  • NY_RobNY_Rob Posts: 1,369Member
    OP... I have an almost identical setup to yours except I have the UFT-80W. vs. your UFT-100W.
    You mentioned in your first post the boiler was "running rich" for the first month or so. It was possibly running a little hot then too. If you look in the site glass and enrich the gas mixture via the gas valve setscrew you will see the ceramic fiber burner element glow more intensely as you enrich the mixture. That could have contributed to the hot condition. I'd take a good look at the PVC exhaust piping (especially elbows) near the boiler just in case there is any damage.

    If you have your own combustion analyzer it's a good idea to check/record the CO and CO2 levels every six months or so as well. My mixture had somehow "drifted" lower over the winter 2 yrs ago which resulted in a too lean condition producing a "ER:10..Flame has extinguished 5 times" lockout condition and a cold house on a bleak Feb morning. A simple 1/4 turn of the mixture setscrew was all it took to get things running again, but it was odd that it drifted lean over time.

    If this was a DIY install and you have no local parts support, I can post a list of spares you may want to keep on hand "just in case".

    Best of luck with your setup... Rob
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