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TT Prestige 110 E18 and B30

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smadanairb
smadanairb Member Posts: 6
in THE MAIN WALL

Greetings. I recognize there are many discussions, RE: E18 and B30, but I haven’t found the answer to mine. My TT Prestige 110 recently started going into E18 and then B30. I know what the codes stand for, but a few things give me pause.

DHW

The boiler is secondary to solar how water. The DHW temperature is 76 and the boiler is not heating domestic water. The circ pump…works fine. Or does it? Should I increase the Honeywell Aquastat temp to confirm if the circ pump energizes with a call for hot water?

EXPANSION TANK

You know how when you rap on the expansion tank with your knuckle and it returns a solid sound - as opposed to a hollow sound - that solid sound “means” the tank is bunk (leaking bladder) and it needs to be replaced? Before the heating season, the boiler was blowing down water and I traced the issue to the expansion tank. It sounded solid. New tank. No blowdown problem. BUT…the expansion tank still sounds solid. Shouldn’t the tank sound hollow like the tank on the DHW system? What does that mean?

ERROR CODES

I’ve learned that a bad expansion tank could cause flow problems and E18. Could this new expansion tank cause this code?

NO DHW

Oddly, my indirect domestic water tank temp is 75F. The TT Prestige boiler is secondary to solar hot water, but the boiler is not heating the domestic water.


I’ve serviced this boiler myself, having replaced igniters, Venturi, troubleshooting error codes and performing CO analysis. But I can’t seem to connect this issue with a specific equipment failure yet. Thanks for your help!

Comments

  • GGross
    GGross Member Posts: 1,767
    edited January 16

    did you properly set the expansion to the same pressure as your systems cold fill pressure? do you have proper air elimination (not a vent, an air separator). your error codes make sense happening together, the boiler is going off on fixed high limit ( this is a serious failure condition) and with the return temperature being too close to the supply (B30) all signs point to no/low flow condition. that could be a bad pump (boiler pump) or you could have an air problem, low pressure problem (like if the relief blows off and you don't refill pressure to the boiler). after the relief valve blows off due to high pressure the valve should be replaced, boiler pressure topped off, and air purged (not vented, purged) from the system.

    You will want to confirm that any pumps flowing directly through the boiler (boiler and DHW pump depending on installation) are working, confirm you have proper air elimination, boiler pressurized to the correct operating pressure (between 12-18 psi cold fill typically depending, the internal switch cuts out the boiler below 10 psi for reference) confirm the expansion tank is set for your cold fill pressure (must do this with the tank completely detached from the system) and if you need to re-fill the boiler purge the air out that was added with the fresh water.

    IMO you have a flow issue through the boiler specifically. Physical blockage, air, no pressure, a bad or air locked pump, all of these things can cause the issue.

  • smadanairb
    smadanairb Member Posts: 6

    Hi GGross. Thanks for your analysis. My answers to your excellent questions are as follows Disclaimer, you will probably be like “dude, that’s not how you do it!”

    1. Installing the new expansion tank, I measured the factory set air pressure with an analog gauge and compressed that to the factory requirement in the boiler manual.
    2. The system does have an air separator.
    3. The system has three pumps: two pumps serving the baseboard heating and one pump serving domestic how water. The heating pumps work. However, when I call for domestic hot water the DHW circ pump does not energize.
    4. Air and/or low pressure problems. I will admit, the boiler was blowing down into a vessel over the fall, which led to replacing the expansion tank. However, I did not add water to the system. And when I replaced the expansion tank - there’s a shut off valve at the tank - I did not check system pressure. I took off the old tank and put on the new tank.
    5. If the relief valve blows down, you’re recommending the replacement of said valve? I didn’t know that.
    6. And post relief valve replacement, water should be added to system and air purged? I would have to figure out how to do that. Not complaining. Just saying.
    7. So it seems to me based on your experience and analysis: A) there is likely low water pressure from slapping a new expansion tank on. B) There is likely air in the system from the same work. C) The expansion tank may not be adequately pressurized. D) And maybe the DHW circ pump could be air locked?

    Would you recommend I seek a professional tech to troubleshoot these issues? I can take apart and install new parts, measure voltage, do CO analysis, but I’m not sure how to go about refilling, purging and properly measuring boiler and expansion tank pressure. Like…use a garden hose and a digital pressure gauge?

    Thanks for your feedback! I welcome all constructive criticism.

  • GGross
    GGross Member Posts: 1,767
    1. your expansion tank needs to match the cold fill pressure of the boiler, which is dependent on a few things. Manufacturer may set minimum and maximum pressures (safety also requires a certain range) system overall height plays a role as well. Usually cold fill needs to be between 12-18 PSI on residential systems, you set the tanks air side pressure to the system cold static fill pressure.
    2. good
    3. the boiler should be hydraulically separated from the heating loops to guarantee correct flow through the unit. sometimes you can direct pipe them but only if the flow rates are within the required range of the unit (you have a low/no flow condition so probably should have been piped primary/secondary)
    4. if the valve blows down and you lose water you are either going to have a low pressure condition on the system, or an automatic fill valve will add more water to the system, in either case you will end up with too much air in the system, and you need to fill the system to the proper pressure and then purge the air out (purge not vent)
    5. yes, and I think most here would agree. when the pressure relief blows off due to pressure (not just manually opened for example) most professionals recommend replacing the valve.
    6. yes the system needs to be brought to the correct pressure (and expansion tank air side set to match) and the system should be purged of air after filling.
    7. , either low water condition, or too much air. When the relief blows off a lot of makeup water needs to be added. that boiler has an internal low pressure switch that cuts off below 10 PSI so my assumption is that there is an automatic fill valve on the system. this will maintain pressure when there are leaks or PRV blow off, but it will add a ton of air if it needs to fill much water which needs to be purged. The expansion tank is likely factory set for 12 PSI (if a grey colored amtrol tank for space heating) so it may or may not be the correct pressure.

    I think you would want a tech to come out. filling and purging is usually pretty easy, but if there aren't a lot of valves sometimes it can be tricky. Keep in mind that techs are acutely aware that Triangle Tube has gone out of business and like to use that as an excuse to sell a new boiler. This is an older unit and may be getting close to retirement age… but your current issues seem to me to be system related, the boiler should be OK for a bit yet, assuming you don't have some sort of physical blockage in the heat exchanger (sludge etc)

  • psb75
    psb75 Member Posts: 1,109

    You'd better make sure that the DHW circulator is working i.e. when energized, it should move water. Make sure the impeller will spin. If so, also make sure that it is not air-bound.

  • smadanairb
    smadanairb Member Posts: 6

    Hi GGross. Thanks for your feedback.

    1. The expansion tank is the Amtrol tank for space heating.
    2. It sounds like I need to replace the PRV, fill (maybe) and purge (certainly) the system to correct pressures considering the amount of blow down. I will research how to do that.
    3. Do you have recommendations for the proper gauge to measure system pressures? And tools I should need? I know that’s probably asking for too much!
    4. I haven’t had great success getting an hvac contractor to visit. I’m a bathroom remodeling contractor, so I tend to take things on myself - always looking to learn and become self sufficient.

      thanks!

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