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Plate Exchanger???

GMP Member Posts: 3
Hi. Iam heating my shop with outdoor wood boiler. Technically NTI boiler is primary and wood boiler is secondary. Have been heating whole season so far with the wood boiler. My question is about the plate exchanger. In the picture you can see the black tube with two green pex coming threw middle which comes from wood boiler. Then threw the plate exchanger and back to wood boiler. Pump for that loop is located out on wood burner. Should their be some sort of bypass when not calling for heat or valve that would open up when thermostat calls for heat and close when temperature is achieved? I believe I am loosing a ton of btus with water just circulating 24-7 threw plate exchanger. Building is 2640sqft, spray foamed walls to around 4", r 50 in ceiling. 2" polystyrene under concrete and down 2' on side walls. The system has no problem heating building. The wood boiler heats our house too. Which ran last season with just the house and I didn't heat shop. Seams to be going threw a ton more wood. Even on a warmer days at 20 degrees it seams to burn about the same about of wood when its -20. Never did that with the house just on wood boiler. Warmer days would burn less wood last year. I had a hvac contractor do the work. If anything looks wrong let me know. Cant wait to hear from someone. Thanks


  • Harvey Ramer
    Harvey Ramer Member Posts: 2,239
    Are you

    burning dry wood? Green wood contains 80% moisture. Hence you need to burn a lot more off it to achieve an equal BTU output of dry wood. Not to mention it craps up the inside of your heat exchanger and slows down the heat transfer. You guessed it. That burns more wood.

    As I look at the pictures, I see a black gizmo that the pipes connect to before they reach the plate exchanger. What is it? What does it do?

    Running constant circulation underground can sap a lot of heat. Especially if cheaper pipe is used. I would switch it to only circulate when there is a demand for heat. And YOU MUST ADD A BOILER PROTECTION VALVE. It protects the boiler from getting downed with cold water. Thermal stress will crack your heat exchanger if you don't.

    It looks like you have black fittings on a stainless plate exchanger. Might want to replace them with brass or bronze.

  • GMP
    GMP Member Posts: 3
    plate exchanger

    I new I was going to see a difference heating both buildings but didn't think would be going threw that much.I also thought the wood may be a little wet. I burned some at the start of season that sat for almost 2 years stored on pallets and tops covered went ok. This last batch iam not so sure about. Seams heaver so guessing to wet. The wood boiler is sized large enough to heat both buildings no problem. The black thing is a Thermostatic valve that had to be installed with wood boiler. Do I still need one on the gas boiler end? I didn't put them in but what is wrong black pipe fittings? Will it wreak plate exchanger. I think it looks horrible. The under ground pipe to shop is about 20' of pipe and to house about 80'. Both buried 4' down. The pipe is ThermoPEX which has two 1-inch pex pipes insulated with high-density urethane insulation. You would switch it so it would only transfer heat to heat exchanger when their is a demand? Will it stress the plate exchanger. What would you use? Sometimes the water drops to about 90 when wood goes low. When running will get anywhere from 140-165 on transfer side. Water comes in about 175-185. Is that what you meant about dropping cold water in which would cause cracking? The gas line just got installed. So it shouldn't get that low once the LP tank gets installed.  Thanks
  • GMP
    GMP Member Posts: 3
    folowup previous post

    90 is what reads on my NTI boiler side after goes threw plate exchanger. The black thing returns water if it gets around 160 coming in. Never had water drop below 150 in outdoor wood burner.
  • Harvey Ramer
    Harvey Ramer Member Posts: 2,239
    The black

    fittings in contact with the stainless causes corrosion.

    Thermopex is a good product. I doubt you have very much heat loss form it. The primary reason you are burning so much wood is due to the fact that it is wet (high moisture content).

    You need to set up a proper dual-fuel control strategy. When the propane boiler takes over, the circulator going to the wood boiler needs to be off. Otherwise you will transport the BTU's back out to the wood boiler. You don't want that. The control needs to measure the actual temperature of the wood boiler to determine whether to make the switch between wood and propane.

    Also the water quality in the system is very important. You need to maintain a PH level of about 7.5 Also on the wood boiler side you need to have a good corrosion inhibitor. It wouldn't hurt to have the inhibitor in all your systems. I prefer Fernox products.

    Since you are setting up Dual-Fuel you will need to add a freeze protection agent to the wood boiler side. Make sure it is a non-phosphorus based antifreeze. If you use a Fernox inhibitor you should also use a Fernox freeze protection agent. The Fernox is non-phosphorus.

    Here is info on the boiler protection valve http://www.caleffi.us/caleffi/en_US/Site/Products/Catalogue~544~544-%3Cjsessionid=392D3BC221E24600FFD16ADD11D27878.www2/args/sezione/Family390_BoilerProtectionValves/path/2~280~280_NPT-details/include/~applications~catalog~serie.jsp/index.sdo

  • SWEI
    SWEI Member Posts: 7,356
    Some reading

    highly recommended before you get much further http://www.caleffi.us/en_US/caleffi/Details/Magazines/pdf/idronics_10_us.pdf