vermontday wrote:Thought it would be interesting to see what everyone is using for domestic water settings and learn from others on how to most efficiently operate in the summer.
I run 4 teeth, a touch over 4 for air (rice coal), and 1.5 minutes every half hour on the timer. 140 LL and 185 HL. I have used 3 teeth before, but for simplicity I just left the feed alone this year.
vermontday wrote:While my wife wants me to dump the heat in our swimming pool (I think Rob does that)
I have no dump zone, and have never found the need for one. I allow gravity circulation between the EFM and my oil boiler, so the extra thermal mass helps keep things at a steady temperature. All piping and both boilers are insulated, and usually stay around 160-170 F. I use a well-insulated 80 gallon indirect for DHW, and I enjoy the steady output of 120 F water.
vermontday wrote:EFM's using a tankless coil run differently in the summer than one with a separate superstore. I believe the Honeywell L7224 aquastat will run towards the low limit setting with a tankless coil, as it is just water temperature pulling in the stoker. In a system with a superstore, it runs towards the high limit setting.
In our system, the superstore appears to the aquastat as any other heat zone would. When the zone valve turns the circulator on, the boiler gets ready for a big heat load and turns the stoker on. Since the stoker at 3 teeth is putting out more btu's than needed and it takes a while for the circulator to reheat the superstore, the boiler overruns the call in btu's and the stoker shuts off on the high limit.
While all this is fine and the domestic hot water needs are satisfied, the result is the boiler temperature is near or above the high limit setting most of the time. This leaves little room for the outfire (hold fire fluff) timer to run the stoker.
My system is wired the same way you just described, and I have no issues with overheating.
Are you running a circulator off C1/C2 in the L7224 aquastat? If not, just disconnect the end switch from the TT terminals and let the stoker fire off the low limit.
If you are driving a circulator off C1/C2, move it to a relay independent of the L7224...then the unit will behave like it has a tankless and only fire when the low limit is reached.
Also - That Superstor should "hold back" the EFM with only 3 teeth of feed. As per the manual, the Superstor needs to be piped with 1" pipe, 1" full port zone valve (if used), and it needs 10 GPM of flow through the coil. The manual says the coil alone creates 8 feet of pump head, so it is possible that the coil inside the indirect may be underpowered and not transferring heat from the boiler properly. Another possibility is calcium deposits on the coil from hard water...that will result in a small difference in temperature between the boiler supply & return pipes on the indirect.
vermontday wrote:The plan would be to wire an additional 6006a aquastat to the input of the Logo, set it at 170(?), then when a natural call for heat occurs, the Logo would let the stoker come on with the L7224 for 5 minutes, then after which it would only let the stoker come on if the temperature was below the 6006a aquastat setting. This would hopefully end up leaving temperature lower when the call for heat was finished. This would leave btu room for the outfire timer later to come on without going over the high limit.
I think it would be a lot simpler to disconnect the end switch going to the L7224, but maybe that's just me. Don't over complicate a simple problem with additional controls...KISS.