solar tank heat

radmix

Thanks Bob, Thats how I had it in my original bid. But of it was cut out.

radmix

solar tank heat

I'm on a project where the plumber has installed a Buderus solar tank for dhw and space heating model # PL750. I am contracted for the heating. The tank on the heating side holds 120 gallons of water, the domestic side holds 80 gallons of water and there is a solar coil at the bottom. There are 2 sets of pipes that I am using on the tank, one set is for DHW demand if the tank drops below 120* this circ. will come on to satisfy the DHW needs. The other set is piped so if the tank is above 140* It draws heat from the tank to satisfy the heating load. I have heat traps on all four pipes to prevent heat migration from tank to heating system. the traps are 16" deep on all four pipes but when the tank that has maxed out @ over 200* just last weekend there is an extreme amount of heat still migrating out of the tank. The problems that I have are that when there is not enough sun to maintain the tank for DHW, My boiler has to heat up a combined 200 gallons of water that does not sound efficient! and when the tank is to hot even thermal traps are not enough to prevent heat migration. In my original big I bid it out to have a 40 gallon tank as a side arm and the solar tank to feed it the DHW so I am not heating up 200 gallons of water on a demand for hot water. ant suggestions will be appreciated.

Bob Gagnon plumbing and heating

Use

Two tanks and harvest the maxium amount of energy.


Thanks, Bob Gagnon

EJ hoffman

If you pipe it right you don't heat up all that water

Call Buderus they can help you with the piping, if done correctly the system really works great. You need some extra controlls but it will really work.

Unknown

Why does it

heat the 120 gal heat tank when there is a call for domestic, it should only heat the 80 gal domestic tank to a temp below 140? Spring loaded check valves work well for heat migration, you have to drill a very small hole in the check for thermal expansion.

hot_rod

looks like

you have some options on the boiler piping. Use the uppermost taps to limit the amount the boiler heats. It looks like a very clever tank with that stratification lance and multiple connections.

Hook a wood or biomass boiler to the largest volume

I recall Dennis Bellanti using a tank like that, at his place, in a rather unique fashion!

http://www.buderus.net/LinkClick.aspx?fileticket=o9G1IIXJ0EU=&tabid=592&mid=1547

hr

radmix

solar tank heat

It will always heat the 120 gallons of water on DHW demand that's how the tank is designed. I have also looked at piping diagrams in the Caleffi solar book, most diagrams for DHW and space heating eather use a two coil tank or a thermal storage tank . neither show how to deal with heat migration. Also because of the 120 gallons of water I had to go from a extrol 30 to a extrol 90 for the thermal expansion.

Eric_6

PL750/2S Thermosiphon Tank

Actually boiler side volume is at 73 gallons and condensing
boiler should be piped as Buderus shows (roughly heating the top 1/2 of the 73 gallons). Sensor locations are Very Critical. This tank works due to high level of stratification thru the heating lance making sure heating is from the top down letting solar heat the coldest water.
Yes, do call Buderus tech support and they can give more info and help out on DHW thermosiphon issue.

Regards,

Eric