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Design updates for ModCon Boiler in 100 year old high mass gravity system

24

Comments

  • PC7060
    PC7060 Member Posts: 1,155
    @Hotrod - "You mentioned a 120 SWT are you sure running a 30∆ will give you enough output at the end of the road?"

    Certain rads get the heat sooner and the TRV close when satisfied. Then the next set get the heat and so on.

    This will be similar to my current setup. My current boiler runs on a "15 seconds on / 120 seconds off" cycle the vast majority of the time. The microcontroller has logic to increase run time and and shorten off time based on RWT but this only occurs on the coldest days (10-15 DegF).

    The constant 5 GPM based on 30 degree delta should give me long boiler runs. May need to change the high end of the SWT for coldest days once the systems is up ad running and addition are closed in.
  • PC7060
    PC7060 Member Posts: 1,155
    edited August 2020
    Working on the size of the expansion tank....
    From Engineering toolbox Closed Systems Expansion Tank Sizing for max temperature of 180DF, the recommended tank size is 10% of system volume.

    System volume is about 120-130 gallons so looking for a 12-13 gallon capacity.
    https://www.engineeringtoolbox.com/expansion-tanks-d_885.html


    The Extrol product chart tops out at the Model 90 with 11.3 max acceptance volume. Is this with the acceptable range? Planning on a max operating temperature in the 120-140 range but sized at 180 for safety factor.


    Current system has what looks like a 40 gallon old school tank hung in joists.

  • hot_rod
    hot_rod Member Posts: 22,024
    try the sizer at Amtrol or Wessel, the commercial one allows you to put in volume, pressure, temperature rise.

    It is sometimes less $$ to install 2 tanks. #30 & 60 are common at most suppliers.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • PC7060
    PC7060 Member Posts: 1,155
    edited August 2020
    @hot_rod - The Amtrol site was interesting. The commercial option had several inputs as you said but only specified commercial series tanks. The residential selection control was very primitive (type = cast iron radiators, enter BTU hr.)

    I cranked up the BTU to 175k correlate to the capacity of the system rather than the heat load; system recommended a SX-30V Extrol Expansion Tank (14 Gallon Volume), a floor type tank which pretty much matches the specs of the hanging type model 90.  

    The floor mount actually simplifies things a lot. I can connect it to the existing water input line right ahead of the legacy pump flange ( see below, ignore Mrs. PC's Vermicilli worm bag, the worms like the warm boiler area during cold weather :neutral: )
    Researched circulator pumps based on a really informative training session conducted by Dave Holdorf (@Dave H_2).  Still like the Taco 0015e but tbe Grundfoss ALPHA2 is a strong contender too.  Either pump will work fine at the lowest setting due the the very low head of the fat pipes in my system.  
    Both pumps come configured with the flange mount which should allow me to connect to existing return and pipe up new system return from there. 
     
  • hot_rod
    hot_rod Member Posts: 22,024
    Is the Taco 0015E a delta P circ? With the TRVs you want a delta P to maximize flow and vary the speed. Taco does have delta P not sure which models they are.

    Assuming you are using a separator or buffer, the delta P on the distribution, the boiler circulator could be a fixed speed.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • PC7060
    PC7060 Member Posts: 1,155
    edited August 2020
    Yes , the 0015e is a delta P, Low : 5 head; Med : 10, High : 18 head curving down (pump running full out). 
  • PC7060
    PC7060 Member Posts: 1,155
    I’m going to clean the system before starting the new install using Sentinel X400.  The boiler is currently off for summer but I can program the controller to run the pump to circulate the cleaner. 

    Does the boiler need to be running hot water to effectively clean the system?  
  • hot_rod
    hot_rod Member Posts: 22,024
    PC7060 said:

    I’m going to clean the system before starting the new install using Sentinel X400.  The boiler is currently off for summer but I can program the controller to run the pump to circulate the cleaner. 


    Does the boiler need to be running hot water to effectively clean the system?  
    Grease, oil, solder flux, pipe dope, all seem to clean out better with hot water.

    You would also want to circulate through every circuit and loop, not just the near boiler piping..
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    PC7060
  • PC7060
    PC7060 Member Posts: 1,155
    Thanks @hot_rod, I’ll cycle up the system and let it run for several hours With 4 quarts x400 to give it a good flush. I’ll do another run with clean water before starting the updates. 

    Regarding the indirect water heater tank,  in reading Virginia Plumbing Code I don’t see any language requiring a double wall tank. The CA 2019 code has specific language for allowable single wall tank with labelling along with double wall requirements. 

    Are double wall indirect water heater tanks required by the 2012 or 2015 International plumbing code?
  • mattmia2
    mattmia2 Member Posts: 9,576
    Double wall requirements are relatively rare. the tank is at higher pressure than the system so water leaks from the tank in to the coil. most system chemicals are formulated to be nontoxic for this reason as well. the water in a boiler is considered to be low risk. if you use toxic chemicals in the system then you need an rpz backflow preventer instead of just a double check valve backflow preventer on the prv.
    PC7060
  • hot_rod
    hot_rod Member Posts: 22,024
    This double walled requirement is hit and miss across the US, regardless of the national code, each jurisdiction can require DW.
    I would say systems with ethylene glycol for example, would dictate DW HX.

    Code authorities struggle to define toxic, or worry someone inadvertently adding a toxic conditioner or non-potable glycol, down the road.
    Probably many of us have come across systems with automotive glycol in them :)
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    PC7060
  • PC7060
    PC7060 Member Posts: 1,155
    Finalizing the pipe sizing for the boiler connections to the original 2” supply and return lines.  Do you recommend using the 1-1/4”  pIpe which is the max connection size for the HTP UFT?

    My rigid pro press can work up to 1 1/4 inch” pipe size but given 1” line is max size for my Milwaukee M12 cutter this size would simplify the install a bit.  

    The design flow rate is in the 5-8 GPM range. 
  • hot_rod
    hot_rod Member Posts: 22,024
    1” can handle 8 gpm easily
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    mattmia2
  • PC7060
    PC7060 Member Posts: 1,155
    I'm inserting a DIRTMAG in the return lines at the end of the 2" run before it goes into the pump. Is there a significant advantage to using 2" DIRTMAG onto a existing 2" MPT copper connection to capture the dirt and metal while the water is moving at a slower velocity?

    A few posts back I included a picture of the 2" line going into the old pump. Plan would be the remove the pump flange and connect the 2" DIRTMAG at that point and then downsize to 1" line into the pump.

    I'll be using 1" copper line for the boiler connection as recommended by @hot_rod and could remove the copper section back tot he 2" BP and convert to 1" before installing a new shutoff, 1" DIRTMAG and the Grundfoss ALPHA2
  • hot_rod
    hot_rod Member Posts: 22,024
    really no reason to spend the extra $ for a 2". In the brass version it is the same body.
    This is another option, can be rotated for vertical or horizontal installation. These are common for wall hung boilers.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • mattmia2
    mattmia2 Member Posts: 9,576
    edited August 2020
    Also, get the threaded or union dirtmag, don't sweat it to copper like i did...
    PC7060
  • hot_rod
    hot_rod Member Posts: 22,024
    Thread sweat or press available on most products up to 2".
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • PC7060
    PC7060 Member Posts: 1,155
    Thanks for the information @hot_rod and @mattmia2. I'm going with the 1" NPT 5463 Series DIRTMAG Dirt Separator with Magnet. The 1" lines make things simpler and the pro press connections are much less $ than 1-1/4 (or 2").
  • PC7060
    PC7060 Member Posts: 1,155
    I see Amtrol has standard and Radiant expansion tanks (#30 Extrol Expansion Tank vs. RX-30 Radiant Extrol ).

    I see the radiant type can handle Glycol and snow melt systems, it this only difference?
  • hot_rod
    hot_rod Member Posts: 22,024
    The radiant Extrols are lined inside so they can be used on non barrier tubing installations. The coating protects the plain steel tank from corroding away.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • PC7060
    PC7060 Member Posts: 1,155
    1. looking at the WM Aqua-Plus 45 and the HTP SSU-45 Indirect Tanks. Both are stainless steel units and look to be very similar in price and performance. Am I missing any key differences?

    2. What type of circulator pump is typically used for the indirect water side of the system? Seems like a standard constant rate pump in the 8-12 GPM range is acceptable.

    3. Pg. 53 of the HTP UFT I&O Manual discusses the setting for the Indirect Sensor type AquA or SEnS as aquastat or indirect sensor.

    How do these two sensor type differ in configuration and performance?


  • mattmia2
    mattmia2 Member Posts: 9,576
    1. Look at your water chemistry and the specs for both tanks, especially sodium content and hardness. Also look at the first draw rate. Indirects can make a lot of hot water, but they take a while to start producing it because the boiler takes a few minutes to purge and fire then heat the water in the boiler and dhw loop.
    3. You can put a conventional aquastat on the tank which is just a switch that closes a contact that tells the boiler there is a dhw call or you can use the thermistor from htp that senses temp and the boiler will control the dhw setpoint and differential in the menus and will read the tank temp on the boiler.
  • PC7060
    PC7060 Member Posts: 1,155
    @mattmia2 Thanks for the information.

    "1. Look at your water chemistry and the specs for both tanks, especially sodium content and hardness. "

    Our fine city's annual water report puts the PH in the range of 7.2 - 7.9 and the hardness in range of 21-57 mg/L with average of 32 (soft).

    I'd think that with SS tanks, either the HTP or WM units would have no issues.

    3. RE: "conventional aquastat on the tank which is just a switch that closes a contact that tells the boiler there is a dhw call"

    The Aquastat on the current boiler has thermal probe That kick on boiler hear at certain temperature. Assume this would be same concept.,

    Re: "thermistor from htp that senses temp"
    Are you referring to the OUTLET THERMISTOR 8100P-016?
  • mattmia2
    mattmia2 Member Posts: 9,576
    PC7060 said:

    @mattmia2 Thanks for the information.

    "1. Look at your water chemistry and the specs for both tanks, especially sodium content and hardness. "

    Our fine city's annual water report puts the PH in the range of 7.2 - 7.9 and the hardness in range of 21-57 mg/L with average of 32 (soft).

    I'd think that with SS tanks, either the HTP or WM units would have no issues.

    The water report will have chloride content as well(i misspoke, I should have said chloride. It usually comes from road salt.) Stainless steel doesn't get a long well with water that had high chloride content.
    PC7060 said:


    3. RE: "conventional aquastat on the tank which is just a switch that closes a contact that tells the boiler there is a dhw call"

    The Aquastat on the current boiler has thermal probe That kick on boiler hear at certain temperature. Assume this would be same concept.,

    Re: "thermistor from htp that senses temp"
    Are you referring to the OUTLET THERMISTOR 8100P-016?

    No. There is a themistor you can get that goes in the well in the indirect tank in place of the probe for an aquastat that connects to the "DHW Temp Sensor" connection on the HTP UFT boiler and allows the boiler to sense the tank temp. You set item "39:SA" to "SEnS" to tell it that you have a thermistor connected instead of an aquastat. I think you can order the tank with it already installed or order it separately. I ordered it separately. I think the part number is in the Superstore indirect manual.

    You might look at the superstore ultra commercial with 2 heat exchangers and connect them in series to get a cooler return water temp to the boiler to make it operate in the condensing range more of the time.(although it is unlikely the added cost will ever make up for the added efficiency)
  • PC7060
    PC7060 Member Posts: 1,155
    edited September 2020
    I'm going to add the X400 cleaner to the systems; is it best to drain it down and add cleaner with fresh water? Current water has 1 quart Hercules Boiler Liquid? I have a pot mixer and can add cleaner to system without draining.
  • PC7060
    PC7060 Member Posts: 1,155
    Part A of Pg. 14 of the Superstor Ultra Indirect Fired Water Heater manual says "install control element into the control well and tighten into place with screws on the control body"; pretty simple but does not specify a part number.

    Any recommendations?
  • mattmia2
    mattmia2 Member Posts: 9,576
    edited September 2020
    PC7060 said:

    Part A of Pg. 14 of the Superstor Ultra Indirect Fired Water Heater manual says "install control element into the control well and tighten into place with screws on the control body"; pretty simple but does not specify a part number.

    Any recommendations?

    If you use the thermistor, there is a part number somewhere either in the superstore manual or the UFT manual.

    HTP 7250P-325 HTP, INC. INDIRECT/TANK SENSOR 7250P325

    That is the thermostor that slides in to the well and clips on. If you use an aquastat, that will be different. There is also a different tank that has a little compartment on the side for the sensor/aquastat, that may use a different part.

    Make sure you get some thermal compound to help increase conduction between the probe and the tank.
  • PC7060
    PC7060 Member Posts: 1,155
    @mattmia2 - thanks!
  • PC7060
    PC7060 Member Posts: 1,155
    edited October 2020
    Thermostat question: I'm going to use a dedicated thermostat for the HTP UFT boiler and looking for a smart unit that could provide also system performance data on boiler performance including current ODR ODR temperature and DHW performance.

    Any recommendations? Definitely not a "must have" requirement but am curious.

    If not, I am planning on adding another smart Honeywell unit so I can manage all T-Stat from one app.

    Thanks
  • Paul Pollets
    Paul Pollets Member Posts: 3,656
    I'm currently working on a project of a 100yo Seattle home and the owner is about to decide if he wants to re-use the cast iron radiators, or convert the main & 2nd floor to radiant floor heat using Climate Panels. The original gravity mains were modified at least 2x and will require serious repiping. We'll use a Viessmann CU3A floor mounted condensing boiler which is easy to clean and service. It will most likely require two temps, which is the case for hybrid hydronic renovation.
  • mattmia2
    mattmia2 Member Posts: 9,576
    The t-stat if it can communicate with the boiler will be by the boiler manufacturer. There was an HTP rep on here at some point, maybe they can give you more info. I don't know if the UFT has a communicating thermostat, it is inexpensive because it is bare bones, you might need to look at a different HTP line or a different manufacturer is you want an communicating t-stat. @Ironman has installed a lot of UFTs, maybe he knows more about what HTP has in communicating thermostats. Another fairly costly option is to use a BMS and control the boiler with that but have the BMS do the monitoring.
  • PC7060
    PC7060 Member Posts: 1,155
    Just drained down the old 145KBTU New Yorker boiler and radiant heat systems after running the cleaner for extended period at operating temperature. The water looked like ink so cleaner seems to have done its job.

    I've refilled the systems with clean water and have the pump on to give the systems a good flush before beginning the installation of the HTP UFT80 boiler with HTP SSU45 Indirect tank.

    Are mixing valves standard for the Indirect tanks? I've seen several systems with mixing valve and a bunch without. I understand the mixing valve are required with running the higher (e.g. 140F) tank water temp to reduce water born bacteria.

    Is this required (or recommended) for home DHW systems?
  • mattmia2
    mattmia2 Member Posts: 9,576
    The tank temp tends to vary more than with a direct fired water heater because of the lag between the call for heat and when the boiler purges, fores, and heats the system water and if you ave a long post purge time you will put more heat in the tank but you will get more overshoot. The mixing valve if applied to work correctly at your minimum flows and minimum temp differentials will even out the temp. The best of both worlds would be to directly connect laundry and the dishwasher and maybe the kitchen sink but provide tempered water to the bathroom sinks and tubs/showers.
  • PC7060
    PC7060 Member Posts: 1,155
    So the my initial plan was to use a 45 gallon indirect tank but with a tank temp of 140 it seems like a 30 gallon indirect coupled with the HTP UFT 80 would be more than sufficient for three bathroom and normal usage. 

    Are my numbers off? Does the smaller tank cause short cycling?
  • mattmia2
    mattmia2 Member Posts: 9,576
    I'm not sure that small a tank especially with that small a boiler will give you enough hot water for 3 baths. Are they full baths with a shower or tub? The incoming water temp and the flow of your shower head will make a huge difference.
  • PC7060
    PC7060 Member Posts: 1,155
    @mattmia2 - The house has two standard tubs (rarely used), three showers primarily with low flow Heads. Typically only one in use at any time sizing for worst case three showers.

    I reviewed the SSU technical data and the SSU30N produces 212 GPH (@8GPM) and SSU45N produces 292 GPH (@10GPM). Given this is GPH not GPM and a typical shower is 2-2.5 GPM, I see your point about the advantage of the SSU45.

    Another item of note is the UFT80 nominal flow rate of 7.6GPM so the boiler would not be able to support the maximum output of either tank so a bit more reserve is good plan.


    Thanks for your advice!
  • mattmia2
    mattmia2 Member Posts: 9,576
    Others can maybe give you some calculations on it. I got a 45 gallon ssu and wish I went bigger but i take long hot showers with little flow restriction in the shower head. If you go too small you will notice it, if you go too big all you lose is a little space and money.(and maybe a little more legionella concern)
  • mattmia2
    mattmia2 Member Posts: 9,576
    I should have read all of it before responding...
    Look at the first draw rate table (which last I looked wasn't labeled as such in the manual) and your temp rise. The temp rise in the simple table is not realistic for a 140 degree tank temp and like 40 degree water in the winter in a cold climate. I think the boiler size used is about twice the size of your boiler.
  • PC7060
    PC7060 Member Posts: 1,155
    Wow, that's interesting table, illustrates the hot water is limited by the boiler capacity. Comparing the boiler BTU to an standalone gas hot water heater, the BTU match up to the largest gas units but the tank is 30 gallon less. Tank usage will be slightly lower due to the mixing of cold water to get output of 115F.

    I'm sure its like everything else, no perfect solution but close enough.
  • mattmia2
    mattmia2 Member Posts: 9,576
    At the size of your boiler it still acts as a storage tank in the same way that a conventional direct fired water heater does. It recovers a lot faster than a gas direct fired water heater, but you still have to have enough heat in the tank to cover the peak demands. A tankless water heater is usually 200,000 btu/hr and that can only produce around 2-3 gpm at a 40 degree supply temp.