Over Teperature of EKO 40

[BulldogAcres]

I have an EKO 40 and decided to continue operating it this summer due to high Propane price and I have 40 acres of forest. Due to the low demand for hot water, I only had to fill up the firebox once a day. The EKO ran flawlessly supplying 120 Degree domestic water to the house and apartment. I keep the EKO set at 180 degrees and use a heat exchanger to isolate the boiler water from the domestic and heating water and a mixing valve to reduce the water temperature to 120. This morning I went out to the Shop where the EKO is installed and noticed an over temperature code and the water temperature of the boiler was a little over 240 degrees F. Everything was running fine, the heat exchanger and mixing valve were still supplying 120 degree F. domestic heating and hot water, the pumps were running and there was no sounds from the boiler. I immediately opened the fire box and it was almost out of wood. The EKO had burned a days worth of wood in 12 hours. After a few hours the boiler temperature was down to 176 Degrees F. I turned off the Boiler, turned it back on and it began working as if nothing had happened. I found out that the bypass damper was not fully shut and this allowed enough air to enter the fire box and allowed it to burn uncontrolled. I did a little research on line to find out why the boiler continued to operate without turning the water to steam and never opened the relief valve. I found out that water boils at different temperatures depending on the water pressure. I was fortunate that I had almost 30 pounds of water pressure in my boiler. Water boils at around 240 degrees F at 26 pounds of water pressure. I guess I am lucky that I had that much water pressure in the boiler or I could have turned my hot water boiler into a steam boiler and done some damage.

 

[jebatty]

You are very fortunate pressure did not rise to a point of a pressure rupture anywhere. The boiler likely is OK up to 50-60 psi, and steel/copper plumbing certainly can take the pressure and heat. It is a bit surprising that the pressure relief valve did not activate. You may want to check that valve to make sure it is operating properly. Human error is one think that is difficult to protect against in all situations.

 

[willworkforwood]

..... I only had to fill up the firebox once a day .... I keep the EKO set at 180 degrees ....

I would expect that your EKO does lots of idling (fan off) as a result of a full firebox with almost no call for heat. Is there a large differential setting, giving the boiler a long, deep idle? Do you check the boiler HX (heat tubes) occasionally? One of the negative aspects of lots of idling can be creosote formation in the heat tubes. Creosote in the HX can also happen from burning poorly seasoned wood, and a combination of the two can be particularly ugly. You might also check the area around the damper door to make sure creosote buildup isn't the cause of the failure to close. Not criticizing what you are doing - if it works for you, great.

 

[in hot water]

Good observation, glad you caught that.

While the boiler and piping can stand that temperature it is a bit un-comfortable for pumps and any control valve components. Most hydronic parts are rated to 225F. But an intermittent over temperature should not destroy them.

It's also possible for water to boil at temperatures below 212F, something the "open system" OWB manufacturers and installers seem to forget. In a multi story open system piping it is possible to have sub atmospheric pressure conditions above the boiler. This can lead to steaming and hammering conditions.

Some of the evac tube solar collectors pull a vacuum in their heat pipes. This allows the fluid to boil at 100- 110F and flash to steam. The energy is then scrubbed away at the condensor bulb inserted into the fluid stream.

hr

 

[Duetech]

Sounds like it's time for some storage. In a sense I had a scenario like yours for heating DHW in the summer with an EKO40. I went to partial loads and shut the boiler off after the desired temps were achieved. The dealer I bought the boiler from recommended setting the boiler summer temps to around 155f but no lower. Yes I did have idling but shutting the boiler off at temp. saved a lot of wood and reduced idling time. But i was only heating DHW for a single family unit. Storage would allow you to run a full throttle fire and store the heat and in a limited sense could help reduce the threat from overheating by heating the storage to a little above norm when the human factor goes awry. Or smaller loads would help reduce the overheat risk.