Problem With Buderus GC124 w/ Aquasmart

Superfrog

I recently had a Buderus GC124 Logano Classic with Beckett Aquasmart 7600B controller installed, no indirect DHW. I have a separate hot water heater that's not tied into the boiler system at all. We have an old house from the 1920s, one zone, and the Aquasmart seems to keep the water at a constant 140F. This is keeping all of the radiators in the house fairly warm, and will gradually raise the ambient temp throughout the day. The t-stat isn't calling for heat (set to 68), and the temp in the house will get into the high 70s by the late afternoon. In fact, I've tried 3 different t-stats and still have the same issue. I've checked the low and high limit on the Aquasmart - low limit is at 122F with 18 degree differential, high limit is at 180 with 18 degree differential. Also, turned DHWP on the Aquasmart off. I understand that the Aquasmart will keep the boiler water at the low limit plus the differential (140F) on standby. Is there something I'm missing? It seems like a poor design to keep the radiators constantly warm, and I hate to keep having to kill the power to the boiler instead of relying on the thermostat to keep the house comfortable. Any suggestions?

Robert O'Brien

No flow check? You are getting gravity circulation, nothing to do with thermostats. Install a flow check. Buderus never maintained temp on their CI boilers prior to the GC144, not sure why they do it now. You can turn off the low limit, but you would be going against Mfg's specs

unclejohn

You need to turn the low limit setting to off. The info to do that is in the paper work that came with boiler. The factory default is low limit on.

Superfrog

There's a flow check on the circulator. It's a Grundfos UPS15-58fc. It's mounted on the return, per install specs from Buderus. I was thinking of getting the outdoor reset for the Aquasmart, then the low limit would be disabled when the warm weather shut down kicks in.

Superfrog

You wouldn't happen to know how to turn the low limit off, would you? I've dug through that manual forwards and backwards and can't find it anywhere.

unclejohn

I's in the aquasmart manual.

Robert O'Brien

Superfrog said:

You wouldn't happen to know how to turn the low limit off, would you? I've dug through that manual forwards and backwards and can't find it anywhere.

http://www.beckettcorp.com/protect/manuals/61757_AquaSmartQuickReferenceGuide.pdf

Robert O'Brien

Superfrog said:

There's a flow check on the circulator. It's a Grundfos UPS15-58fc. It's mounted on the return, per install specs from Buderus. I was thinking of getting the outdoor reset for the Aquasmart, then the low limit would be disabled when the warm weather shut down kicks in.

Great in the summer but what about shoulder seasons? To the best of my knowledge, Buderus doesn't specify a circulator location and I can't imagine they would recommend anywhere other than on the supply, pumping away from air eliminator and PONPC

unclejohn

http://www.beckettcorp.com/protect/manuals/61738_AquaSmartmanual.pdf

You can leave yourself with no heat if done incorrectly. Read the stuff twice.

Superfrog

Robert O'Brien said:

Superfrog said:

There's a flow check on the circulator. It's a Grundfos UPS15-58fc. It's mounted on the return, per install specs from Buderus. I was thinking of getting the outdoor reset for the Aquasmart, then the low limit would be disabled when the warm weather shut down kicks in.

Great in the summer but what about shoulder seasons? To the best of my knowledge, Buderus doesn't specify a circulator location and I can't imagine they would recommend anywhere other than on the supply, pumping away from air eliminator and PONPC

I've actually called Bosch and asked them about circulator placement on my GC124. They specifically said on the return. That still doesn't make a whole lot of sense to me - I figured I'd want the flow check on the supply, opening up when the circulator kicks on from the thermostat. Kind of strange, but those are the specs.

Does anyone know if you can run a GC124 as a cold-start? I know it may shorten the life of the boiler a bit, but my main concern would be voiding the warranty.

I think if I can set the over-ride temp on the outdoor sensor to, say, 60F, instead of the factory 70F, for the warm weather shut down, I might be in pretty good shape. In spring/fall it's usually right in the low 60s here, and we never have the heat on until November at the earliest.

unclejohn

In the Buderus sales info they show the circ mounted on the return in one photo and on the supply in another.