new plumbing layout

Looks like drastic differences between the notebook one & the paint one. Are you sure about the paint version? That's all one big loop that would need to run all the time.

Not sure the function of the check valve in the first one - on quick look I'm not figuring out what it's to accomplish.

I think if you want to try to run this with everything unpressurized you'd maybe want your circulators down low on the returns.

No - the original (notebook?) is two loops. Boiler/tank loop, and tank/system loop.

Or am I mixed up on which one is which? You said paint was current so I was thinking the notebook was original.

Also don't think there would be any back flow when that house circ is running - the check is flowing the same way as the house circ. It's also flowing the same way as the boiler circ so don't see an effect there either.

Ok, I was mixed up.

Main thing (I think) when running non-pressurized is making sure the circs have enough inlet pressure. Cavitation & all that. So thinking the lower you can get them the better. So I would try to put them each on the lowest part of the system. Which sounds like the bottom of the tanks?

The other factor coming to me right now is what happens when you want to heat from tanks when the boiler isn't firing & that circ is stopped. You don't want the house circ to pull through the boiler when that is happening. There are some tactics to try to use to prevent it. The main simpler one but maybe hardest to get just right is plumbing it up so there is more resistance (head) to the house circ, from the boiler loop than the tank loop. So something simple like trying to put most of the T's & elbows needed on the boiler loop side vs. tank loop side. I.e., a straighter shot between the tanks and the house circ. One example of doing that a subtle way is moving your house circ feed from that T just right of the boiler circ, over to the right to a T that would come straight up out of tank 1 to your house circ. Similar at the bottom, turn the T around down there so coming from the house return is a straight shot into the tanks and the water coming from the tanks to the boiler has to take more turns.

Another step might be to move your house circ feed from that piping T just right of the boiler circ, to a separate fitting all together in the top of the tank. But that might complicate your piping - you would need separate runs for boiler & house piping to keep the reverse return thing happening. Something else that might help is to have the house circ running a fairly slow flow. Or better, something variable that you can tune flows with - like use an Alpha circ for your house so you can slow it down by throttling with one of your isolation valves. I know if I turn my house circ up faster, it will pull flow through the boiler. But won't otherwise.

@maple1 I drew in the check valve in the return from home in the event the boiler was firing and the house was not calling for heat. That way the boiler would only charge the tanks with heat and not bypass any to the home. I'll have to talk with the OP again to see for sure what he wanted. I thought he was going to a batch burn set up similar to mine.

So circ vs circ, another thing to consider is that your boiler loop will likely need to flow more than your house loop. It will make a lot more heat when it's going, than your house loop would use (presumedly). So a healthy circ on the boiler side would help. I don't know what you have for circs and what the head losses are on each side, but IMO an Alpha on the house side and a 3 speed 15-58 on the boiler side is a decent match. Then, you can adjust boiler flow by the 3 pump speeds to get a decent dT thru the boiler, and vary house flow by switching up speeds on that circ along with throttling if needed. It could turn out to be quite a balancing act.

warno said:

@maple1 I drew in the check valve in the return from home in the event the boiler was firing and the house was not calling for heat. That way the boiler would only charge the tanks with heat and not bypass any to the home. I'll have to talk with the OP again to see for sure what he wanted. I thought he was going to a batch burn set up similar to mine.

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Unless I missed something I don't think that check there would prevent that situation?

It might be trickier to get everything balanced with the house circ running 24/7. If it was a start/stop system a zone valve would likely help. Mine is that type with zone valves.

cumminstinkerer said:

@warno I plan to batch as much as possible but may end up a little off on some days not sure yet. still curious about the amount return to the boiler to get it cool enough to call for fire unless just its radiant loss will be enough to lower it, or will I need to base may draft off tank temps now?

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With all that water in storage you should have lots of cool water for the boiler to draw from, with batch burning, long as you can get flows balanced out. Have you factored in return temp protection? Usually a key consideration with storage - you don't want return water lower than 140 entering the boiler.

What about this? (Real bad photo edit job...)

Basically you don't want to have the house side interfering with the boiler side and vice versa. That should separate them just enough to prevent that while still maintaining reverse return for each.

Don't forget return temp protection. I didn't try to add that in.

@maple1 with your edit in the drawing won't the house return flow "slam", for lack of better term, into the boiler circuit return flow in that tee fitting at the bottom of tank 1? Maybe I'm thinking about it wrong but seems it might cause a fighting effect between the pumps.

I do agree too that a zone valve would work in place of the check valve but they are a bit more money than a simple swing check.

I dont think? The only connection from house return to boiler return is thru the 3/4. Everything else would go thru the tanks. If both pumps are running the boiler circ should be pumping at higher flow than house circ assuming what I mentioned above. So most boiler return should be coming from tank bottoms. This is a bit out of my butt though, I am used to low intermittent load flows.

They have been used before. No reason coming to immediate mind.

As long as it has been vented and washed out you should be fine. Just fill it with water once and drain to get any heavy residue out. Then be sure to double check for any residual fumes before committing to add bongs and fittings. Not that it's flammable but the ammonia fumes can kill you if they over come you.