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Ben

Joined on November 21, 2007

Last Post on September 2, 2010

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any opinions?

@ September 2, 2010 9:34 PM in buffer tank piping

I just wondered if anyone thought there would be an advantage to the closely spaaced tees after the tank or just reversing the connection points shown. It seems the tees would only allow the water returning from the slab to enter the tank. This would also take the most advantage of any solar heat since that heat would tell the boiler not to run once the sun had produced enough heat to meet setpoint. On the other hand, if the water from the slab could go directly to the boiler inlet there would be an even smaller amount of boiler produced heat entering the bottom of the tank but at any time the primary pumps were flowing more than the secondary pumps the tank would start heating from the top down. Which do you think is best?

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@ August 25, 2010 10:24 PM in buffer tank piping

This building is constucted with some foam form concrete walls and the rest of the walls and roof are structural panels on timber frame. All of the heat is slab radiant and the 5 zones are similar in size. The two Knight boilers are 105k btu and the storage tank is an 80 gal. and when bid the coil in the tank was for future solar but they have since selected a contractor for that. The reason the mixing stations are shown pumping away from themixing valves is because that's the way Viega builds their manifold mountable mixing stations. I have since sold the customer on Alpha pumps and will build my own "stations" pumping away from the valve. The bms sets the temperatures shown at 0 modulating to 80 degrees @ 60 degrees. If a zone runs for more than an hour the station will bump up 5 deg per 1/2 hour.
I am sure the bms/boiler temperature probe should be located near the thermometer above the tank and just ahead of the inlet to the mixing stations. I am also confident the outlet from the boilers should be where the present inlet to the boilers is shown. My big question is the best location for the inlet to the boilers. Which would keep the tank the coldest, a closely spaced tee on the outlet of the tank or where the outlet to the boilers is presently shown at the inlet to the tank? I know that the colder the tank the more value they will get from the solar.
I'm sorry I wasn't able to interject ealier but 9 hours of running pex plus 4 hours of driving and an hour helping my 80 year old dad work on his truck kinda shot the day.
Thanks again for your thoughts.

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@ August 24, 2010 10:26 PM in buffer tank piping

I really don't see the need for a "buffer" tank on this job. The only time I've used one is with a bang bang boiler that was feeding four very differently sized reheat coils. This job has five fairly equal radiant zones with two 105,000 btu Knight boilers. The building management system controls the outlet temperature of the two mixing stations based on outdoor temperature and runtime. The bms also controls the boiler temperature by the requirement of the highest operating mixing station. These are the reasons I'm especially concerned by the bms probe being located in the middle of an 80 gallon tank.The bids are already in so I have these parts to accomplish the sequence of operation. Moving connections and parts around will not change my costs but adding anything else would. So the puzzle is the most efficient and flexible way to use the listed parts to accomplish the listed sequence. The best response to this wins nothing..
Thanks for all interest and plans of action