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[sceptre74]

Let's say there will be 25 ft of 1" pex supply to the hx. Will there be that much time before there is 180* water all through the hx

[slimjim]

M a y b e one minute, it will blow cool air for that short time, will that be OK is the question.

[sceptre74]

That is the question. Lol. Maybe I could try it without and if we don't like it, it shouldn't be a big job to install later on. Probably the same as it is now with the indoor unit. The air is always hotter about a half hour after the stove is loaded

[slimjim]

It can easily added any time!

[Scott7m]

Get what email slim?

I got a couple from you  it weren't sure they were for me haha

Back out in the field I go, be back later

[slimjim]

Just a wiring scematic I think.

[idahohay]

Sceptre, I'm planning a system similar to yours and was wondering what 50 plate you were planning on using. They vary quite a bit, I see 3/4 inlets up to 2-1/2" and ratings up to 500,000 btu/hr when pumped at 51.5 gpm. Brazetek states a pressure drop of 7.3 psi when circulating 51.5 gpm in a 5x12 50 plate. (Pretty sure that  has 1" taps) I'm assuming the pressure drop would be less at lower gpm but can't figure out how much less.

Can anyone comment on why this would be better to use than let's say a Brazetek 3 x 8- 20 plate rated at 100,000 btu/hr when the flow is 10.3 gpm and the pressure drop is 5.2 psi?  I picked that model because that would seem like a realistic flow in your design.

The chart from another brand  (GEA) states minimum flow rates for their fphe's stating that if a minimum flow isn't maintained it will leading to premature clogging. What I would like to find out is:

1.  What would be the likely pressure drop in the 50 plate if pumped at 1/5 the recommended rate?

2. Is pumping at less than the manufacturers recommended rate going to shorten the FPHE's life due to internal build up?

[sceptre74]

I have a SEC m31b-50. It's a 5 x 12 with 1" ports. A friend of mine was using it with his indoor oil boiler but took it out and decided to run it straight through from the owb. Slimjim recommended this size. Not sure about the rest of your questions, but I'm sure someone will chime in on them

[Sprinter]

In regards to how long it takes for 180 water to get somewhere, using 4 feet per second it will cover 100' in 25 seconds, 6 ft/sec = 16 seconds. If it takes a long time for hot air to come out of the ducts, slowing the fan speed will fix this. Too must air velocity will cool before it gets a chance to heat sink everything. This is why all the new high efficiency multi stage or I furnaces run most of the time at low speeds. Some run 24/7 constantly and slowly circulating air without feeling or hearing it. This eliminates cold spots and drafts.

Determining head at different GPM flow is hard without a K value or TEL total equivalent length of pipe, because as flow increases head increases exponentially. Seen on most head loss per foot per GPM charts. Mr. Pex for example. Most flat plates are designed to have low head loss. 500,000kbtu or 51gpm and 7' of head is very low. If slightly oversized your always on the safe side.  You would have to have some bad water conditions and some extremely slow water to worry about build up issues. Flow rates much lower than you will ever see, less than 2' per second. Down time is where most of it happens and exactly why some controls have an excercise function built in to prevent exactly this.

Finding a qualified place to do a real hydronic design must be real hard with 23 Ferguson plumbing,HVAC & Hydronic supply locations in Kentucky , 26 locations in Tennessee and more in IN,IA,MO,AR,OH and so on. I guess it shouldn't surprise me that Lowes was your first thought/option.  Especially when you throw around numbers that are FAR from close or accurate. When someone quotes $40/ft prices for underground pipe that anyone can buy 1.25" dual pex flex for $16.00-$18.00/ft or 1.5" logstor dual for $22 or single pipe logstor 1.5" for $12.00/ft =$24/ft for both S&R runs. Do you do that to scare people or because you just don't know cause you've never bought or quoted it. Those are over the phone quotes to anyone, not contractor dealer costs. 85 watts versus 125 watts? You must of meant 33 watts for a small 15-58 and 240-320 watts for large pumps. $75 pump (common,easy to find) versus $350 pump.... $30-$33 per year versus $290-$340 electricity usage. A small reliable application and one stressed and way over any recommended specs. I've done all kinds of radiant systems, but I still have an engineered plan done every time to ensure the customers investment is properly installed and working. I don't learn on the job at their expense

[Scott7m]

Good grief sprinter, do you always have to be a jack ass?

 

I have more stuff in my truck bed than my local Ferguson for this business, they are horrible

[Sprinter]

Here is a drawing using John Siegenthalers hydronic design studio software, on primary secondary. Just think of the buffer tank as the flat plate in this case.  And an except from Bob Rohr in Missouri on pri/sec piping.

" The primary loop circ is usually a low head, high GPM circ. It's ONLY job is to move fluid around that circulator loop. It doesn't move any flow through secondary loops. Either the Grundfos 15-58 or Taco oo7 on speed 1 will usually be fine for that. To move 150,000 BTU at a 20Fdegree delta T you need to move 15 gpm. look for a circ to do that job at a low head, some of the DHW recirc pumps are great, but expensive as they are usually bronze or stainless volutes. "

[slimjim]

Nice drawing sprinter BUT I do not see any true comparison to a non pressurized OWB, this appears to me to be a pressurized indoor boiler that uses thermal convection to transfer the heat from the indoor boiler to a buffering tank without the use of a circulator and then from there to 1 circ feeding multiple zones, I see no similarity to a primary secondary heat loop at all, this will not work on an OWB period.

[idahohay]

I was thinking the same thing as slimjim.  Was trying to figure out how the pressurized boiler was supplying water to the buffer tank. I don't see the primary secondary loops.( wrong drawing?)

Moving 15 gpm through a buffer tank with very little pressure drop would seem a lot different than 15 gpm through a fphe with a pressure drop of 5 psi or more.  15 gpm at 11 or more feet of head is beyond an 007 and maybe the 15-58.

I hope to learn from this thread as I am about to make some decisions related to this.

[NaturallyAspirated]

Nice drawing sprinter BUT I do not see any true comparison to a non pressurized OWB, this appears to me to be a pressurized indoor boiler that uses thermal convection to transfer the heat from the indoor boiler to a buffering tank without the use of a circulator and then from there to 1 circ feeding multiple zones, I see no similarity to a primary secondary heat loop at all, this will not work on an OWB period.

I would say I disagree with you.  That symbol is what John uses as for wood gasification furnace.  For a pressurized furnace he would have used a different symbol.  I would bet the wood gasification circulator was inadvertently left out.

Neal

[yoderheating]

 Slim do P&M gassers have a pump run 24/7 like ours do? Most high efficiency furnaces I've seen have to.