Upon doing all the reading I could find I'm looking for an experienced answer. What I have is a single loop hot water zone on the first floor (slant fin baseboard). I'm redoing my kitchen and some baseboard needs to go and a kick space goes in it's place. Originally I thought I could run the main under the floor and use the one mono-flo on the return with a 15" spacing. It seems I can't do that but I can get about 3' of straight pipe under the one new cabinet. So the question is feeding a KSH on the flat, do I use one or two mono-flos? TIA

 

You can also just install one monoflo on the return and leave a full port ball valve in between that tee and the regular tee on the supply line. That was you can purge any air from that circuit and also if the one monoflo isn't quite strong enough (it should be), you can divert more flow by partially closing the the valve.

 

Thank you for the answer, especially the part about that the 3/4" valve will help in the purge.

 

Here's another way to do it that is proven and works just as well or better.
Install two 3/4 x 1/2 x 1/2 tees with 1/2 going to kickspace S&R and 1/2 feeding the bypass. The reduced bypass will create the additional pressure to force flow to heater. As before, install a full port ball valve (1/2") between the two tees for ease of purging and additional balancing if needed.

With no monoflo tee(s), smaller ball valve and reduced piping, money is saved accomplishing the same principal.

 

ZL, I like your plan! but me personally would use a good quality globe valve in the bypass... I wouldn't wanna listen to that ball valve hissin' away at me if it were throttled... they can get noisy. I don't mean one of them cheapo big box m.i.C. rubber seat valves either ... a REAL valve ... with a teflon seat ... the kind that are made for this service ...

 

Trooper,

9X out of 10, the series loop is passing right by and the ball valve/valve would then be wide open, only there so you dont have to reach up into cab to manually vent.

 

I was kinda thinkin' that it would mostly be open wide enough that you wouldn't hear it ... but I mean, what if you _did_ have to throttle it ... you might want more than roughly half the flow going into the kicker ... and you might have to crank that thing down a bit to do that ... I dunno ... there's really not that big a difference in price between the two ... if any ...

but I think yer right, a ball valve is probly fine.

One thing to be thinking about though... that kicker is gonna suck some heat outta that water ... anything downstream might not get the BTUs it needs ... just a thought.

 

So true, with a loop having a properly designed flow rate of between 1-4 GPM, you shouldn't hear anything. SS trimmed ball valves have been used for years on closed loop HP's to balance flow from 1/2-5 GPM (1 GPM per ton).

No doubt the kick space needs to be calculated to watch max Delta T desired, with radiation beefed up at the end of the circuit, with a K-42 unit worth about 7', K-84 about 13'

 

This installation may not be as touchy as thought.

I installed a kick-space heater operating off a 1" monoflo main. The supply and return to the KSH are 1/2" copper. The supply and return tees are only about 8" apart.

But here is the "kicker" (pun intended): The tees are just regular tees (not monoflo). I get sufficient flow to the KSH just from gravity (the KSH is about 12" above the main) and a tiny pressure drop between the tees. (The reason for not using monoflo tees is another story - the rest of my original system does have monoflo tees.)

And, the temperature drop in the main, between supply and return tees for the the KSH isn't significant.

My KSH has a fan with undoubtedly helps promote gravity flow.

When most monoflo systems were originally installed, the hydraulic calculations were often minor in any. Based on the drawings for my 60-year-old monoflo system, it's pretty clear that it was "designed" based on seat-of-the-pants experience: 1-1/2" boiler piping connections, feeding two primary 1-1/4" supplies (one for first floor and one for second floor), each supplying two 1" zones, and all radiator risers 1/2". More than likely, the installer either just went by experience or went by one of the the sample layouts in the B&G engineering manual. Maybe he had the B&G rep eyeball the drawings, and bless them? Or maybe the installer figured if there was a problem, he could solve it by adjusting the balancing cocks.

Here is a quote from the B&G 1954 engineering manual: Many designers have considered it necessary to successively increase the size of the heat transmitting units because a portion of the water passes successively through them, resulting in a lower average water temperature for the distant units. Experience, however, based on thousands of actual installations, indicates that this is not necessary....

In other words, it ain't all that critical.
Doug

 

I'm not so sure that I would call it gravity flow. I think some water will just go that way so that the water doesn't have to move so fast through the one inch main between those 2 tees. That said, I would say someone would be fine doing this on short runs but if any changes in elevation or longer runs are needed, the flow won't have much incentive... and will need a monoflo, and maybe a secondary restriction.

How far is it from those regular tees off your monoflo main to your KSH?

 

You're right - it's a pretty short run, maybe just a couple of feet.

I'm not advocating skipping monoflo tees, and I wouldn't do it again.

But I don't think adding a KSH will significantly deplete heat from downstream radiators.
Doug

 

Certainly the circ chosen for the system has alot to do with it. Perhaps over pumping.
I'd be curious to hear what your Delta T's are for the two loops for comparison.

 

Delta T across headers - measured with Omega magnetic pipe analog thermometer:

2nd Floor N = 18 deg F
1st Floor N = 16 deg*
1st Floor S = 17 deg
2nd Floor S = 16 deg

*The KSH is on the 1st Floor N header.

Delta T at KSH:

On the 1" header between the supply and return tees = 2 deg

Between the supply and return 1/2" copper legs = 10 deg

Overpumping? By comparision to a nominal 20 deg temperature drop, I am overpumping some. But I think there are benefits from overpumping - the monoflo tees will divert a little more flow, possibly improving performance for the longer branch runs. My piping flow noise is satisfactory. My Taco 0012-F4 circulator is rated 1/6 hp, 1.57A, 115V which would be 180W. The electric cost would be about 2 cents per hour or running time. But that pumping power all goes into the heating system.
Doug