Time Delay Relay on Pressuetrol Circuit

Rod

I saw a post on this the other day by Larry C and I know several people were experimenting with relays last winter. This got me curious.   Does anyone have some real world feedback on whether there is any benefit to using a DOM relay to slow the boiler cycling?

- Rod

David Nadle

In a word, no.

Rod, I played around with timer relays for two reasons. The main reason was that after a long cycle my boiler enters a state of one minute on, one minute off cycles until the thermostat is satisfied. It takes a long time for the first cut out (around 10 oz.) so this short cycling only happens on the coldest days. The second reason was that after 30 minutes of steaming I had some gurgling radiators and thought giving the condensate more of a chance to return could help that.



On the main reason, delay on make will eliminate some short cycles, but as long as all the iron is hot the on cycle will be around a minute anyway. In the end I felt that the timer relay wasn't worth it.



On the second reason, the various relay experiments didn't help at all. Ultimately, cleaning the water and adding a dose of Hercules cleaner silenced that problem.

Rod

Time Delay

Hi David- Thanks for the reply. I remembered you were experimenting in this area and was wondering how it worked out. My problem is we have a large house and shut down unneeded room in winter (using TRVs) and this makes the boiler way oversized. I initially tried a delay on the thermostat as it didn't have a cycle function but since then have got a new thermostat with a settable cycle function.  I was then going to try the delay between the pressuretrol and the burner, but decided to remove it as I would be away traveling  and didn't want to confuse a tech. if my wife had to call one in an emergency.

May try again this winter.

- Rod