Buffer tank

NickFl

mattmia2 said:

Is the indirect a separate circulator or is it zone valve controlled? There are menu settings to control if it is its own pump or there is a system pump that comes on with a dhw call.

Separate circulator wired into boiler terminals dedicated to domestic hot water.

NickFl

Quick update. Everything is up and running. Looking back, everything was relatively easy. What confused the heck out of me , was the bad, brand new thermostat wire from the indirect water heater. Now the heating zones are controlled by Taco SR506-EXP-4, and hot water controlled by the PHR100.
Big thanks to Fred and Ezzy from Creative Solutions Plumbing for their suggestions, and finding time for it.

mattmia2

So you have the indirect set up with the htp thermistor instead of an aquastat?

EzzyT

@NickFl glad we could help.

NickFl

mattmia2 said:

So you have the indirect set up with the htp thermistor instead of an aquastat?

HTP 7250P-325 tank sensor that came with the HTP ssp30.
Fortunately I was able to talk to a competitive person at HTP. That was after one of the HTP support reps, suggested to call the manufacturer of the sensor. The translation is: don't call us, call the manufacturer of the sensor, which is us.

NickFl

One thing I need the help with. Some time ago, during renovation, I ran a dedicated hot water return line, intending to hook it up to drain line on old electric water heater for gravity recirculation. Never got to it. Now I connected it to HTP SSP30 auxiliary tube, which results in hot water to get to an open faucet twice as long, due to hot water pushing from both sides of the loop, which basically doubles the distance the water has to travel from the water heater. My plan is to put a recirculatory pump with the check valve. What is the right equipment and the right way to do it?

mattmia2

You need a check valve for the reason you indicate. You need a stainless or bronze pump, not an iron pump because it is exposed to fresh oxygenated water unlike a heating system where the air gets quickly taken out. Probably a check valve on the inlet to prevent it from flowing back in to your cold water system and an expansion tank on the DHW system because the expanding water can no longer flow back to the main or well tank. There are numerous control schemes, time of day timers, demand timers with a push button, continuous run. If you go with the continuous run option, which I don't recommend, you need to heavily insulate your piping because the piping essentially becomes an extension of the storage tank.

hot_rod

Not sure what you mean water "pushing from both sides of the loop"?

Does the tank have a thermostatic mix valve? if so the recirc piping is different.

If you add check valves to the cold supply to the tank, you need a thermal expansion tank. They are code in many areas regardless of the check you add, as the water supplier my have a back flow valve installed in your supply.

Good info on piping and sizing the pump in this issue
https://www.caleffi.com/sites/default/files/file/idronics_11_na-r2.pdf

mattmia2

My assumption was he hooked up to the return for a record pump without the pump so the water from the tank was flowing through both the supply and the return.

hot_rod

mattmia2 said:

My assumption was he hooked up to the return for a record pump without the pump so the water from the tank was flowing through both the supply and the return.

When you open a faucet water will flow to that fixture through the path of least resistance. Usually the supply is a larger 3/4, the recirc 1/2. So the water should flow out to the fixture on the original supply.

I suppose if the supply and recirc piping were exactly the same size, length and number of fittings flow could split.

Really doesn't matter if you are adding a pump and check, it will flow in only one direction. The direction of the arrow on the pump.

Think small on the pump size, it just needs to move enough gpm to keep the loop warm to the farthest fixture. The math to calculate that is in the tech journal I attached above if you are a numbers cruncher. Most people guess at recirculation pump sizing

Insulate both supply and recirc piping to reduce pump size and operating cost.

NickFl

Back from 3wk vacation. The system works fine. Taco 006e3 ECM installed on SSP30 auxiliary outlet(inlet) with check valve and cheap aquastat. No need to use cold water supply. No more dumping cold water into the septic tank. The original plan was to use gravity, but since both lines were connected to hot water outlets on the water heater, it didn't work.