Hydronic system stopped working

[Alternety]

The system has run for 10+ years. Two days ago it stopped. Floor heat may have been off for a few days. The house seemed chilly, but I did not go downstairs and look at the boiler sytem at the time.

System - Weil-McLain Ultra-80 Series 2 boiler. Tekmar Zone control 369, boiler control 262. Assorted quality pumps.

Boiler supports DHW and infloor heating. Large number of zones.

Boiler shows message saying return water temp too high.

I powered off the whole system and reset the boiler. After that it decided to heat the DHW. But nothing else. Ther are thermostats calling for heat; but nothing happens. The pump between the boiler and a storage tank for the floor, and the pump that runs the loop with the circuits for the floor heating. Nothing.

I went through the settings on the 262 and 369 controllers. I don't see anything obviously wrong.

I have not had heat for 2 days. It is getting annoying.

Any ideas on why this could happen? It was all working; then not. And DHW working and the floor parts not working is odd.

Ideas for how to troublshoot appreciated.

 

[Jadnashua]

Are you saying that the circulation pumps are not energizing? That's fairly easy to verify that they are getting power. If the pump is getting power, but not turning...it probably needs to be replaced. Most of those type pumps rely on water to lubricate things, so if the system is dry, you may have toasted them.

Does your boiler have a primary/secondary loop? Without the circulator pump(s) running, there is no radiation, and the primary loop will almost immediately get too hot on the return...i.e., no heat is being extracted to the secondary loop. You need flow on the secondary loop to heat anything in the home, and to keep the return temp on the boiler low enough to then try to reheat it once it gets back to the boiler.

 

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[Alternety]

I am going to stop posting here and open essentially the same problem as a new post. I will redirect attention to the Tekmar controllers. It is a more accurate point of discussion.

 

[Alternety]

This post seems to gather the most views, so I will update here as well as another post of mine.

THE SYSTEM HAS WORKED JUST FINE FOR 10+ YEARS. SOMETHING BROKE.

I am still trying to find the failure point. My wife is less than enthused at my resolution progress and got an extra down cover for her bed.

A bit more information on the configuration.

1 x 262 and 3 x 369 Tekmar controllers are used. Old equipment.

There is a boiler loop, with closely spaced Ts. There is a pump on the boiler for the main loop. Another pump on the main loop with closely spaced Ts feeds the HDW loop and another does the heating loop. HDW has priority. For building heating there is the closely spaced tap to circulate water to a buffer tank.

The top level loop that feeds the individual radiant heat valves is provided with a fixed speed pump. I have issues with that fixed speed pump and a bypass device I do not understand. Less than half of the heating surface is actually used. Large zones of the full calculated heating load are just not used (e.g.. garage, everything in the basement).

DHW works fine. No problems.

The pumps for the buffer tank and the system circulation do not activate. Nor does the call for heat from the 369s activate the boiler.

I am going through the wiring trying to figure out what is failing. I have found a number of poorly applied wire nuts and I am replacing them with the larger sizes they should have. Some wiring have been questionable, but upgrading them has so far not been effective regarding the problem.

So far, it seems either a relay controlled by the 262 has failed (two relays used for the two pumps for the loops for the heating zones), more wires are not properly installed, or the 262 is faulty. Not really narrowing down the problem.

There is a pretty good chance that the 262 has a problem. But I have not yet determined that.

Troubleshooting ideas very very acceptable.

 

[Alternety]

Found it. Badly installed wire nut. Sat quietly for 10 years and decided it did not want to work anymore. One wire wrapped around the insulation of the other wires with apparently just a hair hitting metal. I was redoing some wire nuts that I felt were the wrong size. I bumped one in the wiring maze and the system started up.