I've been doing some work at a new Wall-mart super center east of Denver in Aurora and I just think the way they have this system set up is so neet I thought I would sare it with you. I don't know the square footage of the store but it's huge the biggest biggest Wall-mart I've been in.
The hydronic system works on two stages. The first low pressure stage runs at 30 PSI and is the stage the generator exhaust heat exchangers and the low pressure waist oil burners are tied into. Then a second stage pumps bumps the sysem pressure up to 60 PSI on the main loop where the 45 airhandlers and radiant floor heat and snowmelt loopes are tied into.
The store is partially powerd by 6-55 KW natural gas generators, the flue gas off these generators is pumped into a heatexchanger in the boiler room.
The gerator exhaust is then ran through these two heat exchangers. I was geting a 10º rise off these exchangers. The exhaust gas temperature entering these heat exchangers runs around 650º.
Boiler one is a waist oil berner set up to burn the used cooking oil out of the many kitchens in the store.
Boiler two in the system is located a mile away in the car shop where the waist oil is used to bring the return temperature up at the far end of the loop before it makes it's way back to the heat exchangers.
And this bad boy is the guy that gets the work done. This 7 MBTU/HR Rite boiler can take care of the whole facility on the coldest of days. It was around 60º today and the main boiler only fired once the whole day so the smaller boilers and heat exchangers do a good job of keeping up on mild days.
The main heating and cooling loops are circulated with 4-20 HP VFD motors.
Then on top of all that they have a couple arcers of solar pannels on the roof and this.
It's a very impressive setup however due to the fact that they have low and high pressure boilers tied into the same system the TNP on the low pressure waist oil burner blowes when it's circulation pump shut down or there is any kind of pressure spike on the high side of the system. I had to make some adjustmenst on the boiler feed regulatior but I finally got the pressures set to where I got good circulation at the far RTU and the TNP don't blow every day in the car shop, as long as they leave the pump on.