This Friday's case, the case of the lost heat call

RayWohlfarth

In this case, the customer called and said all 4 boilers were off. The boiler sequencing was done by the building's digital control system, something I hate doing. I would rather they send us an enable or disable signal and let us control the boilers but I digress. When we arrived, the building and hydronic loop was cold. All 4 boilers were off. While there, the first boiler started and stopped after a few minutes. I noticed the call for heat light was not lit on the Rib Relay. A few minutes later, the light light followed by the boiler. It shut off after a few minutes. As usual, I will let you know Friday at 6am EST. Thanks

ratio

The BMS supply temp sensor was failed & the system though the water temp was sufficient so it never felt the need to fire the boilers.

Or possibly a similar failure with the OAT sensor, keeping the system in WWSD.

Sylvain

- somebody played with the control panel;or
- the controller has failed; or
- one of the sensor is defective; or
- something is heating the outside sensor; or
- there is no flow and the little hot water at the supply temperature sensor statisfies the controller;
- ...

EdTheHeaterMan

Plug it in?

Turn it off then turn it back on?

Check the modem?

Push the reset button?

Was that RIB one of Adam's ribs? If yes, then it is all Eve's fault

mattmia2

Installed in the winter, now it is warmish out and triggering warm weather shutdown. Trying to make DHW only and didn't put in the right logic to still allow that when it is warm out.

RayWohlfarth

Wow lots of great guesses. I love that about our industry. Just when I think I have it figured out, a new twist is added. The problem was the boiler heated so quickly, it would shut off on the supply water temperature. The supply temperature sensor was really close to the lead boiler outlet. Since it was milder weather, the loop didnt need much heat. The solution was to relocate the sensor to the return and everything worked great.It's almost like the Karma Gods say, That Ray is pretty cocky. Let's throw him a curve. LOL here is the link to the video. Thanks everyone. https://youtube.com/watch?v=zS2RvBQCWxI

The Wire Nut

Hi Ray,

It's been a number of years since we met at the Wetstock at the General Society and I showed you the boilers, etc. I'm a control system freak, hence my nickname (thanks Dan!) of the WireNut, of which I'm very proud! In any case, I really enjoyed this detective case and the way you taught that control "engineer" a lesson. Too many "engineers" design stuff but have no experience in the field they design for. Every engineer should work in the field first and learn their business first hand and, especially, to understand that things will have to be serviced. No matter how clever your design and features, if it can't be installed without issue and more importantly, serviced in the future, it's junk!

All the best and thank you for these greatly informative cases.
Alex aka WireNut

RayWohlfarth

@The Wire Nut I remember meeting you Thanks for the tour. I dont like being petty on a job and never embarrass anyone in front of another person but in this case i made an exception. Funny thing is I used to be a control tech, spending several years with Johnson Controls. Thanks for watching Alex!

The Wire Nut

@RayWohlfarth If you are ever back in the city, and want to continue the tour, just let me know!

I prefer wires to pipes, though it's almost the same, just moving electrons instead of molecules!

Thanks for the detective cases, brings me back to my Sherlock Holmes days!

Alex