Our new setup, is something wrong?

How are you sending the heat to the barn? Is it with burried pex? If so, have you checked the temperature of the flow coming from the boiler where it enters the barn? There could be enough loss there to drop the temperature to around 160 °F.

Just took another look at your photos. I don't see a circulator on the water heater side of the heat exchanger. Are you using the heat exchanger to just preheat the water?

I would be using a down pipe on the PRV. That looks scary if it blows off.

Will

I've worked PT on daries for quite a long time, and yes the water has to be stupid hot. If you really want 170deg. water you probably have to change the thermos. in the heater. Stock ones don't go anywhere hot enough. Do you run a pipeline or are you washing buckets? On a pipeline I thought it was end of cycle temp that mattered.
As far as the heat xchanger. There will be standby losses with a water heater just sitting there. If you are just running the incoming(cold) water to the WH through the xchanger you are going to have to draw a lot of cold water out first (if the WH is off).
As fred stated if you want to heat up the whole tank of the WH you are going to have to put a pump somewhere in there to circ. water through the exchanger, or put on a sidearm. The recovery time with a sidearm is slower but you should have about 12 hours to recover unless you are crazy enough to milk 3x a day.
The simplest thing would be to just preheat the incoming water (with the xchanger) and leave the WH on to finish bringing the temp up the last few degrees and maintain the standby temp.
You should at least turn the WH around and point the TP valve at the wall. Right now its probably about what, face level. TSK, TSK.
One last thing, IIRC, the boiler water and the WH water should go in OPPOSITE directions through the xchanger. If your hot boiler inlet and your cold inlet both go in the same end it's not going to work as efficiently.

Relief valve should be piped to within 12 inches of the floor as per the Canadian Plumbing code. As for heating your hot water, what is the supply temperature at the heat exchanger? Hard to heat water to 170 if your supply temp is only 170, especially the way it is plumbed without a circulator on the secondary side. If you do add a circulator make sure it is bronze or stainless steel. If it was my setup I would add a thermometer on the primary supply side, a bronze circulator on the secondary side, and since I have one laying around, a honeywell aquastat to control the 2 circulators to heat the tank to the desired temperature. There would be different control options but my experience with controls is limited, maybe others could chime in here? If you do anything, pipe that relief to the floor, although chances are slim of it happening, you do not want a face full of steam if that valve were to blow due to a malfunction of the tank's temperature controls.

Should also add, for the most efficient heat exchange pipe the primary and secondary supply lines so they enter the exchanger is opposite directions.

memory said:

Yes it is buried pex, the kind that is in a 4" pipe with insulation around it. I checked the temp by putting the probe on the metal T coming out of the heat exchanger, the piece that the green pipe is connected to and at one spot I was getting a consistent 186 degrees so I don't think that is the problem. The thing is the second pic is how it is set up now and we are only getting up to 145 with the water heater. What do you mean by a circular? We are trying to heat the water with the heat exchanger.

Willman, what is a down pipe and what is PRV?

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First....PRV is Pressure Relief Valve which is the valve on the top of the water heater. It should be fitted with piping that goes down to the floor. This is so that in case your pressure gets to high from tank pressure getting to hot, the Relief valve opens and relieves the pressure so the tank doesn't blow up. Without the added piping, it would blow out steam at your face height.

Right now, what your doing is only moving water on the domestic water side when you have a faucet opened. Without a added circ moving water all the time, your only going to get water as warm as you are now. If you added a really small circ, then the water would constantly be moving through the flat plate heat exchanger and heating up the tank slowly until it is as warm as the boiler water. If you do change and add a circ, make sure you add some sort of tempering valve to limit the water temp going to any faucets that you could get burned by. 180 degree water will burn in a matter of seconds!

Me and Mr bud lite spent the afternoon together, Here is what I see first picture post heater, second picture preheater. You need to put a pump to circulate the water threw the HX and around the water heater. If u use more than a tank full for wash down then you will need to add another tank for storage-- this will all work if you have 186 degree water from wood boiler. The pressure relief [called a T&P] needs to be piped to a few inches off the floor.

A prv is a pressure relief valve. I think he means the Temperature Pressure valve ( TP valve). You should come out of the center blank fitting on top of the WH and elbow it down and terminate near the floor.
In your first pic it looks like you are just trying to "boost" the temp of the water coming out of the heater. This should be the way to hook it up if you are trying to turn off the WH.
In the second pic you are heating the water going INTO the heater. If you turn off the WH, there will be a lot of cold water in there that needs to be cycled througb-4 you get any hot water.
You should have some documentation that came with the xchanger that give you temp and flow vs temp rise numbers. This will gve you an idea of what kind of temp you can got out of the xchanger with 186 feed water at any given flow rate.

A prv is a pressure relief valve. I think he means the Temperature Pressure valve ( TP valve)

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Yes, I stand corrected thanks. Could be a huge problem for the unfortunate one that happened to be nearby if it let go.

Will

THERE ARE SOME fellows on this site that know a lot about pump sizing, but i would have to say you could get away with a pretty low cost small capacity one ....maybe 150 bucks...since it only has to circulate a small distance and the BTUH draw is low...do a google of sidearm hot water heater and you will get some good instructions over on the arborist site..as well as Im sure there are good ones here also. If I recall, sidearms often T into the bottom drain to do thier loop thing..you can tie into bottom drain and still have a boiler drain.

of course, maybe it would thermosyphon if you had the heat exchanger lower..so you would not need a circulator..but Im not sure if that will work well through a flat plate HX...

good luck

oh..one more thing i think the circulator or pump nees to be bronze if its in contact with domestic water..someone at plumbing store can confirm that...

I see you posted on arborist site also.
OK so here goes. The thermos in the WH will only go up to 160. If you are just trying to "boost" it up to 170 then you should stay with pic #1.
If you stay like pic #2, you are just preheating the cold water going into the heater.
IIRC you posted on arborist that your DHW supply was what 52-53? If you are trying to raise that to 170 that is a change of almost 120 degrees. I don't think there is anything that will reise the temp that far for a reasonable amount of money. Start thinking at least 3-5k. $$$$ Unless you are only drawing a half gallon a minute.
In typical milkhouse use there is not a huge amount of water used. I think you said 20 gal. You must have bucket milkers and be washing manually because if you had a pipeline between the warm rinse and hot wash with a 3-4 milker wash tank youd probably be using around 40-50 gal twice a day.
If you want to turn off your water heater altogether then yes you'll have to put on a sidearm or a circ pump. Currently the only time the HX is heating water is when water is flowing out of a faucet and you are drawing water through the HX.
Since winter is nearly over and you'll probably be shutting the boiler down soon the easiest/cheapest thing to do would be to get the correct thermos for the WH and use the HX to preheat the water goin into the WH. You can spend the summer looking at other options.

Think of it this way.
Say the HX will only raise 53 deg. water 70 deg at x flow. You could preheat the incoming WH water to 123 and then let the WH finish the temp rise (50 deg) and maintain that temp.
Or you could let the WH take the well water from 53 deg to 160 (107 deg) and then let the HX take it to 170 (10 deg).

Yes the HX should be more than big enough (for domestic hot water) but you'd have to get one about a gazillion (kidding here - only a little) times bigger to take well water to a 120 degree rise at probably a 5 gal per minute flow rate.

BTW I picked up some grundfos 15-58's at a local supply house for about $90.00. They are three speed and even on the low setting would move WAY more than enough to recover the WH(storage tank) in a 12 hour time frame.

Between here and the other site you should be headed in the right direction by now. Hope everyone has helped.

I've got a quick ?
Is that PVC pipe? You may want to look at the printing on the side of it. I don't think PVC is rated for 170 degrees. IIRC it will end up looking like it has been in the sun too long (brittle and flaky) with continued exposure to high temps.
Not absoluely sure but it may be worth checking into b-4 you have a "catastrophic" failure/

Looks like cpvc not pvc - should be good to 200F.

What flow rate do you need?

I do not think that picture 1 nor 2 will keep up with your gpm if higher than 4gpm and will not heat unless your wood boiler is going.

You may want to put the hx on the floor and run a pump from the water heater drain to a brass t where the tp valve is located - BE SURE to place the TP valve at the top of the t.

Search this forum for "sidearm" and look at http://www.radiantdesigninstitute.com/page75.html and have the "to heating" go to the heat exchanger in the opposite flow direction from the wood boiler to get the most heat.

Evidently everyone that has posted since I did agrees with what I noticed. That is, you are trying to heat incoming domestic water with one pass through the HX. It's not going to happen! If it were mine, I would install a small circulator on the WH side in order to circulate the stored water through the HX until the water reaches the desired temperature which should be controlled by a thermostat. Laing manufactures such pumps and I believe you can get one with an integral thermostat.

the post about a side arm is really what you need, it hooks onto the drain valve at the bottom of the tank and onto one of the ports on the top of the tank, it has a larger outer shell of water and an inner pipe with your boiler water going through it, it will maintain the water in the tank at almost the same temp as the boiler water in the HX.
Adding a pump to circulate through the plate HX you have will do the same thing, but require electricity to circulate. If it were me I would make or buy a sidearm HX and keep the plate HX on the outlet side of the water heater. The sidearm will keep the water heater from having to come on very often, if ever, and the plate HX would add a little extra to any water coming out cooler than the boiler as the water in the water heater cools off during use.

Depending on the design of your hot water tank, you can possibly disconnect the bottom element in your tank and use the existing bottom element thermostat to control a circulator that pulls cold water from the bottom of your tank, sends it through the plate hx, and then puts the water back on top of your tank.

Sidearms are great as long as they keep up with your demand, but with the price of copper, it wouldn't be that much more to buy a stainless circ and use your existing hx. That looks like a pretty good sized HX, and installed with a circulator should produce copious amounts of hot water.

cheers

memory said:

So according to most of the guys on here, I need to either install a sidearm or install a small pump to circulate the water back through the heat exchanger. Since a 30 plate heater is not big enough to heat the water in one pass, would installing a bigger plate heater do the job in one pass or is it just not possible to heat the water enough in one pass?

Right now the water is getting up to 165 with the water heater. We may put a light on the water heater so we can tell when it is on. I also tested the temp of the water coming from the stove and I was getting 186 on the return line. So there is not much heat loss if any. I tested by touching a sensor on outside of the line.

The pipe we are using is cpvc so it can handle the hot water.

I really appreciate all the help so far.

Click to expand...

A bigger hx than what you have is going to cost way more than a new stainless steel pump. And as someone else mentioned... it's tough to get water temps as high as you need them with just one pass through a hx when the water coming out of your well is around 50°. I vote for circulating the hot water. With a 30 plate hx and a circ, you will have more hot water than you know what to do with.

cheers

Anything (almost) is possible. Two key questions: 1) do you want or need to heat 50F well water in a single pass to 170F output? 2) how many gpm of 170 degree water do you need and for how long (total gpm draw at 170F)?

If you want an unlimited supply of 50F well water heated to 170F output at 5 gpm, then software for calculating the sizing of a plate HX on a single pass shows the following. This calculation assumes you can provide 15 gpm of 180F water from your boiler with a 40 degree temperature drop, and that is 300,000 BTUh, which is a very sizable boiler, and properly sized boiler supply/return lines to meet this requirement. If you change any variable, then the size of the plate HX is likely to change. See Flat Plate to do your own calculations.

Side A:
In 180
Out 140
Flow 15 gpm
Pressure drop 1.7 psi (3.9 ft if head + system head)
Size circulator to provide required flow at total system pump head

Side B:
In 50
Out 170
Flow 5 gpm
Pressure drop 0.2 psi
Limit flow through plate HX to 5 gpm

Size of plate HX: 5" x 12" x 40 plate x 1-1/4" ports. On *bay this plate HX is available for around $230.00.

You should see much better results now.