Stress testing my hydronic heater.

Apr 5, 2009
2,774
Catalina '88 C30 tr/bs Oak Harbor, WA
Yesterday the forecast for Oak Harbor called for freezing temps this morning and that does not happen very often so I figured that would be a good change to stress test my hydronic heater. I headed out at 9:00 pm and the temp inside Papillon was 54º. I fired up the Espar S3-D5E and in 5 minutes had enough hot water to turn on the fans. After 15 minutes, the thermostat read 56º but the air was comfortable enough to take off my jacket.
I had taken my laptop along to get some work done and ended up going to bed after midnight. I turned down one fan that was louder than the rest which reduced the heat output a bit. By sunrise, the temp outside was 30º and the inside temp had dropped about 5º from the high the previous night.
The Espar was running on low burn but I was not getting enough heat out of the fan-coils to keep up. I changed the valves to the engine pre-heat settings which circulates the boiler fluid through the engine and in 10 minutes there was a 500-lb chunk of 140º iron under the settee. In the next hour the cabin warmed up and the fans shut off for the first time all night.
I used only battery for all power and after 15.5 hours, I used 87 amp-hrs for an average of 5.6 AH/hr. This was for a cold start from 54º and I had all fans running for 12 hours except for the one which only ran 6 hours. I also had the fridge on and ran the inverter to keep the laptop running due to a bad battery.
Pretty happy with that result.
 
Apr 5, 2009
2,774
Catalina '88 C30 tr/bs Oak Harbor, WA
I am not sure if that is stored in the computer or not. it is all handled by its internal ECU. The way that it works is it fires at max until the fluid reaches 75C (167ºF). It then adjusts the burn between 17,000 BTU and 4,435 BTU to try to maintain constant 75C (167ºF). If the heat demand is low enough that the fluid temperature rises to 85C (185ºF) it enters "pause" where the burner turns off but the water pump continues to run. When the fluid temp drops to 70C (158ºF) it refires at minimum burn and adjusts to attempt to maintain 75C (167ºF).
I have a muffler installed and the unit is very quiet. The loudest part of the Espar is the water pump. Most of the time I could not tell if it was running due to the sound of the 5 fans in the system but know that it was off on several occasions. After I switched in the engine to the coolant loop, it spent much more time in "pause" given the amount of heat that was being stored by the engine block. That also heated up the cabin quite a bit from the engine warming the bilge and radiating through the engine compartment walls.
 
  • Like
Likes: jssailem