2 videos this week, Hot Rod sent me a video on backflow preventers and i talk about time delay relay

RayWohlfarth

In Hot Rods video, he discusses troubleshooting backflow preventers. It's really interesting. Here is the link to Hot Rod's video.

https://www.youtube.com/watch?v=Er_13wzGseo

My video is why should you consider a time delay relay for your cast iron hydronic boiler.

https://www.youtube.com/watch?v=-xvuaDkxVaQ

PC7060

Good video, Ray (and Dan). I like to use ‘hold on break’ type delay relay to set control the minimum call for heat times for boilers with ODR controlled SWT.

for example, on this system I used a Littelfuse relay that triggers on thermostat call from heat to set 24VAC call for heat signal to boiler. When the call for heat signal drop, the delay on break relay holds the signal high for a user defined period of time. If the call for heat goes high during the time out period, the period is reset extending the runtime by the programmed time.

On the low temp ODR controlled system shown below, I used a 17 minute delay on break time. On high temp SWT systems, a shorter delay would be used to prevent overheating during the timeout period.

RayWohlfarth

@PC7060 I like that idea Have you done before and after to see what sort of savings you got?

PC7060

@RayWohlfarth - The delay was implemented one year after install primarily to improve comfort. While house is well insulated with heating load of 10 BTU/sq. foot at 11F design day, effects of sun heating of high mass exterior wall would cause periodic tstat cycling; 10-15 minute off / 1 minute on occurring over 2-3 hours in evening. Adding the Littelfuse delay on break relay eliminated the problem. I recently checked the statistics on the boiler (80KBTU modcon). Over the four years since installed the boiler has average run time of approx 63 minutes per ignition call. Prior to implementing the relay the average was around 30 minutes. Note: boiler also provides indirect DHW heating which brings down average from the long heating runs.

RayWohlfarth

Very cool Good thinking on that. Thanks for letting me know