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[donahuej]

Wrapped up my install here are the particulars:

From OWB one zone 400' of 1" pipe driven by a B&G PL-36 pump to 30 Plate HX then to 1st Water to Air exchanger (both in the crawl space) and then to 2nd Water to air in the attic (up 10 feet or so one story rancher).  I've tried to figure the head pressure but the only thing I figured was my head hurts from all the pressure....

Question:

Any quick and dirty way to tell if the one pump is enough?  I have another PL-36 and or a NRF-22 I was thinking of putting on the return side not sure thoughts?

PS I understand that an open system has a tough time pushing water up...just not sure how tough.  The system is working just want to hear what you guys think.

Thanks,

Jamie

[RSI]

Is it 400' each way or round trip? I would try just the one PL-36 pump first. I just put one of them in my house any it really moves the water. (I think it is doing close to twice the flow rate of the Grundfos 26-96 I just took out)
If it isn't enough then add the second PL-36. They are made to work together and 2 of them can go up to 72' of head.

It should not be any trouble pushing the water up there. The return water going down will help pull the supply up hill so it make very little difference.

[donahuej]

Thanks for the reply RSI - 400 round trip.  I just added the second HE in the attic (two weeks ago) and my domestic hot water does not seem as hot thru the plate exchanger.  I would assume this is hot water flow issue?  Maybe I was spoiled not having the additional HE and longer run in place last spring..I know the PL-36 is a beast I just wonder if I'm asking too much with all elbows and additional run to the second HE.  What are the symptoms of an undersized pump? 

[RSI]

400' round trip should be no problem at all for that pump.

[willieG]

maybe this is the wrong place to jump in and ask this question but it may be of some importance for the  gent who asked about his low heat at his other HE

why does anyon put everthing in series on one feed line?

here is my thoughts ont he matter and please correct me if i am off base

i feel (not proof jsut randome thought) that each heat exchanger in series will slow the flow of the water as it leaves the exchanger (lets say if you are delivering 20 gallons a min. to heat exchanger 1 it slows the flow when it leaves exchnager nubmer 1 to 10 gpm so 10 gpm goes to the second HE it goes in at 10 and leaves at 7 and then this goes to the next one and enters at 8 and maybe leaves at 6 ((these are just random numbers on my part)

now lets say you have your system on a feed and return and each HE has its own feed and return line. unless these HE are all drawing water at teh same time you (in my opinion) have better water flow and hotter water at each and every one.

even if they are all drawing water at teh same time they will get a little less gpm but they will all be getting the same temp water

if you have your He all in series each one down the line (if all are using heat) will be recieving cooler water than the one before it

lets now say at 10 gpm you are drawing the heat down 20 degrees  that would mean in series your third He would only be getting water that was 40 degrees cooler than HE number 1  so lets say number 1 was at 180, 2 would bet water at 160 and 3 would get water at 140

now lets say because you are using  a header system your delivery to the HE would be a little lower that 10 gpm so we say you may draw downn the heat a little more lets say 25 degrees leaving each exchanger but each exchaner would be receiving 180 so heating your rooms would be much easier only the temp returning to the boiler would be cooler

all these numbers are ficticious but i think i can get my point across if i am correct?

to keep the boiler return water up to less than 20 degrees less than the feed water you would just need to increasy your gpm supply

does anyone think i am on the right track here? or hae i lost it?

i have my home on a header system and from the boiler to the house is 250 feet plus all the pipes in the house wwhich amount to about 300 feet of either 3/4 copper or 1/2 inch pex , and my little taco 0011 is doing the job.

[RSI]

If you are running under 10GPM the heat exchangers won't slow the water down much at all.
If you have them on a manifold setup you will either have to use zone valves or you are sending a lot of the water right back to the boiler and the GPM to each heat exchanger will be much lower. You can get by with a smaller pump with it all in series sometimes.

The main reason for putting everything in series is it is a lot simpler and works fine.

My house has a 10 plate, 2 water to air heat exchangers and a dryer on a manifold setup with no zone valves. With the old pump I had, I had to close down the valves to the water to air heat exchangers to get hot enough water out of the plate. Since changing the pump to the PL-36 they are all wide open and water out of the plate is hotter than before.

[willieG]

rsi im not sure i follow you e returning water to the boiler fster or not used?

my header consists of five outlets on to the hot water heater coil for domestic, one to the furnace plenum (controled with azone valve on a thermostat becasue my furnace blower is designed to run in low speed 24/7 so i control the flow of water) an outlet to the floor heat (also controled with a zone vavle and thermostat) and 2 outlets for rads in my basement and inside a fireplace. water rund continuously to the domestic coild and 2 other rads. by by these each receiving theie own water all the "appliances in my system get equally hot water. if i wer to have all these in series on one line my first rad will be getting 180 degree water and each rad after that would get cooler water as each rad in series would be lowering the tempature.

im not sure how much each rad lowers the temp but that would depend on gpm and the starting temp of the water and the amount of air passing over it.

i guess if you have a big enough pump you can deliver all this in series as long as you are moving a lot of water. but there is alos a disadvantage of in series as far as i am concerned. if you have to take an "appliance" out of service for any reason you either need a bypass loop or you have to shut your whole system down to do your maintainence work?

a lot of new houses are going with domestic water headers to assure better water pressure and more even hot water delivery so i thought i would do the same with my furnace water. it works well with my small taco pump and it is fairly cheap to run.

i know with this small pump there is no way i could run all my "appliances" in one single loop, my last HE would be getting luke warm water. when my home furnace is drawing heat the exit temp is 20 degrees cooler than input but all my other rads are still getting the maximum form the furnace. i will agree if they were all inline then the gpm would be higher and the outflow from the furnace rad would be hotter but i dont think it would be exiting at the same temp it was entering at. and it is with the header system i use.

i may be wrong but i am stubborn

[rosewood]

Every hx is going to add head pressure to the calculations . I believe the 40 plate hx I have alone was adding 12 to 14 ft of head pressure? Added to line size and length  it adds up quickly .

[RSI]

Every hx is going to add head pressure to the calculations . I believe the 40 plate hx I have alone was adding 12 to 14 ft of head pressure? Added to line size and length  it adds up quickly .

I really doubt a 40 plate will be anywhere close to 12ft of head loss.
I posted a chart above for a 18x18 heat exchanger. It is around 2.5 feet of head loss at 12gpm.

[RSI]

rsi im not sure i follow you e returning water to the boiler fster or not used?

my header consists of five outlets on to the hot water heater coil for domestic, one to the furnace plenum (controled with azone valve on a thermostat becasue my furnace blower is designed to run in low speed 24/7 so i control the flow of water) an outlet to the floor heat (also controled with a zone vavle and thermostat) and 2 outlets for rads in my basement and inside a fireplace. water rund continuously to the domestic coild and 2 other rads. by by these each receiving theie own water all the "appliances in my system get equally hot water. if i wer to have all these in series on one line my first rad will be getting 180 degree water and each rad after that would get cooler water as each rad in series would be lowering the tempature.

im not sure how much each rad lowers the temp but that would depend on gpm and the starting temp of the water and the amount of air passing over it.

i guess if you have a big enough pump you can deliver all this in series as long as you are moving a lot of water. but there is alos a disadvantage of in series as far as i am concerned. if you have to take an "appliance" out of service for any reason you either need a bypass loop or you have to shut your whole system down to do your maintainence work?

a lot of new houses are going with domestic water headers to assure better water pressure and more even hot water delivery so i thought i would do the same with my furnace water. it works well with my small taco pump and it is fairly cheap to run.

i know with this small pump there is no way i could run all my "appliances" in one single loop, my last HE would be getting luke warm water. when my home furnace is drawing heat the exit temp is 20 degrees cooler than input but all my other rads are still getting the maximum form the furnace. i will agree if they were all inline then the gpm would be higher and the outflow from the furnace rad would be hotter but i dont think it would be exiting at the same temp it was entering at. and it is with the header system i use.

i may be wrong but i am stubborn

What happens when all the zone valves are closed?
Your zone valves also give you some head loss and the small pipe (you mentioned 1/2" pex and 3/4" copper) also. When only one loop is opening your pump is probably only able to supply half the water as it does when more are open. A 0011 is not a small pump. A lot of people are running 007s that max out at 10' of head. (at least that is what the chart I just looked at shows, I thought it was closer to 18)

What I am trying to say is there are a lot of people that run multiple heat exchangers in series and never have any trouble.

[RSI]

Here is a picture of my setup. It was done about 8 years ago. The water is being split and the PL-36 is supplying more than enough to every loop. The 1/2" pex is for the dryer and it is flowing continuous right now. I have an Asco red hat solenoid valve on it but it seems to have failed. (supposed to only open when the dryer is calling for heat)

[donahuej]

Any harm in adding a second smaller pump on the return side? I put the main pump in my crawl right after my thermopex comes thru the foundation.  I have the eletric and switch right there...I might give it a try and see what the results are....As I said I just added the second 16 x 21 HE and about 80 foot round trip to the one loop....I don't mind the added eletric and I like the idea of a back up....

This is a great site - everyone might not agree but we all get along - cool thing  that's not to common these days

[RSI]

If you put in the second pump I would not turn it on unless the big one fails. The PL-36 should supply plenty of water.
It will cause more restriction though and won't move much water by itself.

[willieG]

rsi i have been misunderstanding you ( ithink) it looks as though you have a header system as i do? i am talking about when there is only one supply line that goes to a heat exchanger (say in the furnace) and then out to a domestic plate exchanger, and then maybe to a dryer exchanger. what i  am saying is the last exchanger will be recieving only warm water if it is the last in the long line, and all were using heat at the same time.

and i have myself 2 rads on 1/2 inch pex and the hot water tank for domestic on 3/4 copper that are always wide open (no valves) that move water always. the only things on zone valves are my heat plenum (because my in ground furnace is designed to run the furnace blower 24/7 in low speed ((and this speed heats my house with the OWB)) and also my floor heat is of course on a zone valve.

i am not sure how much heat loss is in the water but if you look at your chart and say (for what you might be able to figure easily) youtook 10,000 btu out of your 180 degree water as it passed thorugh your HE, what would the temp of the water be leaving it? now if that water went to the next HE and it was not 180 degrees it could not get the full 10,000 btu out of it becasue the chart is designed for 180 degree starting water temp. then when the water left the second HE it would be cooler yet and when it reached the 3rd HE in the line, this HE would not be able to get as many btu as the second one. that is why i dont like a one pipe system.

i think i read a chart that said 180 degree water can deliver 100,000 btu per hour at 10 gpm but as you cool the water delivery the btu per hour drops quickly. perhaps it is not enough to make a difference on a normal winter day but on those cold nights when things are working hard the last rad in the single line could very well (only in my opinion) not be able to meet the heat loss of the room?

[rosewood]

RSI,is that chart for a water coil that goes in a air plenum? Doesnt look like a flat plate chart.