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New Boiler and Radiant system setup questions.
Hi, I have an Attack DPX35 Profi gassification boiler. I have done research and read/utilizing the Modern Hydronic Heating book as my reference (awesome book highly recommend!). I am currently setting up and installing the system and boiler. I am looking for others input so comments and questions are all welcome.
I did my own sizing the system for heat loads and head.
House is a 1848 historical cape. Basement (boiler/ storage) has insulated walls and concrete floor, 1st floor has been remodeled (insulated walls and air barrier installed), and 2nd floor is not insulated currently awaiting remodel after boiler is setup for 1st floor heating. 2nd floor heating will be setup after remodel.
Boiler is an Attack DPX35 Profi gassifier.
Storage is 450-500 gallons open buffer tank with suspended separate coils I am fabricating.
System is radiant floor 1/2" pex-al 8" OC through heat transfer plates, insulated below for 1st floor. (2nd flr will be above floor with heat plates.) Loops range from 180-240' in length.
4 zones. 1st floor 4 port manifold, 2nd floor 5 port manifold, 3rd and 4th zone will be by themselves 1st flr bathroom and 2nd flr bathroom respectively.
Taco zone valves and controller pushed by a vt2218 taco pump and mixing valve, air scoop.
This is a closed circuit heat exchanger coil suspended in tank.
Boiler heating circuit has a mixing valve to control boiler return water temp at a min 140 (went with a taco 5004 mixing valve instead of the danfos vtc511 unless someone has a reason why I shouldn't). Pump is a 007 taco with a 4900 air seperator.
1. For the aftercooling circuit/Dump zone on the boiler to prevent overheating, the manufacture recommends installing a Watts Thermal Safety Valve sts20 to a water line, then to the cooling ports and exit out into I assume a drain. I have heard of many others ideas such as dumping into an existing zone, battery backup, or separate heat exchanger/ dump into storage. I don't like any other those ideas for several reasons and I want something that can actually take care of my boilers full output in case something catastrophic were to occur. With the manufactures recommendation on the water line in and dumping it out, when the thermo valve closes after opening up during overheating, doesn't the water in the cooling circuit remain? If so does it just boil/steam out and leave the cooling circuit empty again?
2. Any one have a alternative to the Watts STS20 thermo valve?
3. For my boiler heating circuit heat exchanger coil, I was thinking of 1" copper coil I would fab up into a suspended coil. I want to keep cost down and haven't found any prebuilt ones that were cost effective. I was thinking of 30' of coil, not sure if that is enough?
4. I haven't been able to find any issues but my boilers CH ports are 2" in size. Going down to 1" from that wont cause any issues? I assume this is normal?
5. On my second floor, the farthest away loop is also the largest run somewhere around 380' if manifold for it is in basement. I was thinking of the 2nd flr manifold on the 2nd flr to reduce the leads for the loops. I was thinking of spliting this loop into two loops but then a bigger manifold, double the longest leads in the entire system it would cost more, double the lead lines I'd have to chase, etc. The manifold relocated this should save me 32' minimum per loop on the other 4 2nd flr runs. To control and adjust flow between the manifolds in different locations I heard globe valves work good? Any ideas and what took look out for with remote manifolds? (I was going to insulate the main lines to and from the manifold. I do have a space in the hall at the top of stairs to have access to it also.)
6. I would like to add a 3rd coil to the storage tank to preheat and take most of the work my electric water heater does currently. Any simple solutions anyone has? I would assume I would need a mixing valve to control the output since the tank will be 140-180 compared to the water heaters 120-130 output?