Boiler piping critique

leegej

Sorry if it’s hard to read well, this weekend I’ll get the sheet of plywood up and draw it out to scale. This piping plan closely resembles another system that has been posted recently.

Piping through a Caleffi sep4 air, dirt, and hydraulic separator. First manifold before the mixing valve is for panel radiators, so I was going to pipe it both series with closely spaced tees, and parallel to give me options. I sized the radiators for 140 degree water. Mixing valve is a taco I series, it and the boiler will both have ODR. All pumps have check valves and isolation valves.

Straight out of the boiler on the supply and return I want to add tees and shut offs for DHW in the near future. The boiler also has an integrated primary pump. All piping will be 1”.

Does it look feasible?

hot_rod

expansion tank on either return port of the sep.

Make sure the mix valve has enough Cv flow rate for the 11 loops
Mix valve could be a manual 3 way, it would track with the ODR reset temperature.

The nicer schematic shows a cast boiler with return protection valve, ignore that. Mainly i want to show 3 way valve piping for your manifolds, and option for expansion tank.

I prefer the exp tank and fill at the sep on either return side. All pumps pump away, cooler fluid there.

leegej

Thanks hot rod. I put the expansion tank off to the side just to free up more space on the 4x8 sheet of plywood, but it shouldn’t be a problem to move it closer to the separator. I can always go high with it to keep the center open. Given how long my corn harvest got drawn out, I ordered my supplies all in 1inch without sitting down and really double checking my calculations knowing I might have to tweak and swap out somethings. I was pretty confident that 1inch would suffice, but naturally the longer I have to think about it without time to verify it I’m nervous I should have gone 1 1/4. With any luck I’ll finish tuck pointing my 100+ yr old foundation tonight where the boiler panel will be and can get the plywood hung. Then I can draw things out to size and get my pencil sharpened to see if my gut was right!

leegej

Given that the boiler is in the basement and all the heat emitters are on the 1st and 2nd floor, I was thinking about changing my piping so the hydraulic separator was at the bottom of the panel and I work up from there. However, reading the literature on the taco mixing valve, it talks about having at least a 1’ drop to create a thermal trap.

I quickly drew a very rough picture, doesn’t have all the pumps or anything as I’m really just asking if I can move the separator to the bottom and work up so all the pex coming out of the manifolds doesn’t have to run past the secondary lines up at the top. Or will it not be as big of a mess as I’m picturing?

hot_rod

Sure, the sep can mount anywhere. I have seen them directly below the boiler in tight closet installs.

I would not worry about thermal drops, be sure the circ connected to the mix valve has a check in it.

Thanks to Cory Page for the pic

leegej

Perfect. All circs are grunfos alphas, all have checks. 1” taco 3 way mix valve has a cv of 4 I believe, almost certain that is going to be a problem. Looking at the taco literature, a 2 way mix valve with a balancing valve will give me tons of cv, 8-10 I think. So might be exchanging that out... I’m having fun learning and designing this, but my head hurts!

hot_rod

What is the total gpm flow thru the mix valve?

Here is what 8 gpm thru a 4 Cv valve looks like, the Circulator would need to be able to accommodate that pressure drop.

As mentioned before, a manual 3 way like this would track along with the boiler reset curve, simple and high Cv. An actuator could always be added, possibly the boiler control has an output for it, if ever you wanted more control.

leegej

First, I totally screwed up on my first post. My number of loops aren’t right and I’m not entirely sure how they got so off. I’ve included a pic of the spread sheet I made right out of the modern hydronics book, I know I triple checked the calculations when I made this spreadsheet.

Three zones:
4 panel radiators on the 2nd floor for high temp (sized for 140 degrees). Current plan is home run from the basement, but going to look into running a larger diameter (1”??) pex to the 2nd floor to a manifold.
1st floor radiant:
Bedroom with two loops totaling 333.94 feet
Living/dining/kitchen 4 loops totaling 1148.94 feet

Using the flow rates off the spreadsheet, my required flow rate after the mix valve is 4.05, while the mixing valve cv is 4.0. If my calculations are right, I can live with that considering my design load was -5 I believe and a 70 thermostat setting. Therefore 98% of the time I’ll be fine.

This specific mixing valve got my attention for its ODR, thinking I wanted to make the most efficient system possible. The boiler ODR will be set to accommodate the radiators sized for 140 degree water. I have no issue going a different route with a manual mixing valve (and likely cheaper valve), but I want to understand how it will work and how to go about it.

Side note, would it be worth piping my high temp circuit both parallel and series. The radiators will be sized for 140 degree water, which gives plenty of room to increase if needed. Is there enough potential efficiency to be gained piping it both ways for options?

hot_rod

140 on design day for the panel rads? They may rarely see that condition, so the required SWT will be lower 80% of the season
Not sure how you pipe both methods?
Home run assures same temperature to each radiator no series no parallel piping required
The piping size to remote manifolds depends on the load, BTU or Gpm requirement

The Cv is just indicating 1 psi drop at that flow number, the valve cv number does not need to match the gpm required and rarely does
You could move 20 gpm thru a 4 cv valve if you have the delta P available
Generally less then a 20 PSID is suggested for sizing

In your case making sure the circ you select provides adequate delta P at your intended flow rate. Better to upsize the valve, not the circulator, Or look at other way to reduce pressure drop
You haven’t supplied enough data for sizing, I suspect a typical residential 1/12 hp circ will be plenty. ECM better yet,

leegej

What I meant by piping the high temp loop both ways is to pipe it with closely spaced tees so the return go go back into the supply for the lower temp radiant loops down stream, but also pipe it so the radiators return could go to the return to the boiler. With shut offs on each piping route, so I could choose one or the other. Thinking that I I could pull more heat out of that water before it heads back to the boiler.

However, I’m planning on running ODR reset on the boiler so is that really worth it? The extra cost in piping would be minimal so I’m not worried about that.