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Heating circuit flow

Tonerlow
Tonerlow Member Posts: 60
edited February 2023 in Radiant Heating
I have a Viessmann 200w retro fitted into a 1250 square foot bungalow. They have it plumbed with a 1/2” copper bypass valve(pictured) to allow the boiler pump to run continually(there is no low loss header in this setup). The valve must be left about halfway closed to push enough heat into the system during a call. This works but we hear the turbulent gycol cycling through that valve 24/7(think of the sound of your water meter running when watering grass) 2 separate heating zones for the basement and the upstairs. The southwest bedroom of the upstairs does not heat to the same temp as the rest of the upstairs. I am assuming it is at the end of the loop and not receiving high enough supply temp. Another possibility is that I need more baseboard in that room ?  My question is, do you think there is too much heating fluid running through the bypass and not enough pressure pumping upstairs to reach the far end of the heating loop? Also, is it possible these flare connections are causing some of that restriction to the flow? They appear to be only about 1/4” in diameter on each side of the zone valve. (Rest of existing system is 3/4”)  

What I would love is the boiler pump to be able to cut out when there is no heat call, this would eliminate the need for the bypass and the pump could send all pressure into the fin tubes. Plumber cannot find coding for the 200w that satisfies this though. 

Only 2 pumps in this system. A grundfos 26-99 supplying heat to the house and a 15-58 for the DHW loop. 

Comments

  • Jamie Hall
    Jamie Hall Member Posts: 23,276
    Some additional information needed here... You mention a boiler pump. You also mention a pump for the heat in the house and another pump for the domestic hot water (an indirect, I presume?). And then you mention only two pumps. Can you clarify that? Then I notice a zone valve for -- I presume -- the heat; is there another zone valve for the DHW?

    Can you take pictures from far enough away so that we can see what pipes connect to what around the boiler?

    I have to admit that I see no reason why any pump should be running when the boiler is off. And I'm a bit puzzled by having both pumps and zone valves on the system...

    On you question on the heat to the back bedroom. Are the various baseboards al connected as a series loop? That is, water comes in at one end and then goes through all the baseboards until it finally returns to the boiler -- with that colder bedroom at the return end of the loop? If so, it is very likely that more baseboard will be needed in that room if the rest of the spaces are comfortable, as just pushing more water through the system will warm everything up, not just that one room.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • Tonerlow
    Tonerlow Member Posts: 60
    @Jamie Hall one boiler/circ pump. Running 24-7 thru the ball valve bypass on top left of boiler. And circulating heat when the zone valves open. (Main floor zone valve is behind gas line/venting in very top right of pic.) 

    One pump running for indirect DHW production. Under boiler on left side.  

    As for the piping I am just assuming that it simply runs in a large loop around each floor. We have been in the house 6 years. It is a 1976 split level bungalow. I haven’t actually seen the piping as the basement ceiling is finished.

    I think the old super hot heated the upstairs more evenly. But maybe I did not spend enough time in that particular room before it was our nursery. Open the door of course helps equalize temp but then risk waking a sleeping baby.  

    I have turned the supply temp up a little bit today to see what happens. (Slope from 1.5-1.6 and shift from 0 to +3 

    this boiler is just over 2 years old now. 

  • exqheat
    exqheat Member Posts: 185
    reducing operating boiler temp to 160 will increase circulation to cool room and cool off hot rooms. If this works, you can install an indoor reset to adjust the temps in the boiler automatically.
    John Cockerill Exquisite Heat www.exqheat.com Precisions boiler control from indoor reset.
  • Tonerlow
    Tonerlow Member Posts: 60
    edited February 2023
    @exqheat This boiler is set up with an outdoor temperature sensor and operates with weather compensation. You are suggesting though that a lower supply temp will even the heat distribution? What is an indoor reset exactly ? 

    I have also been adjusting dampers and trying to find a good balance, so far not great results. I’m wondering about just adding some baseboard on that last room. 

    Also in my long term plan would be renovate basement and do staple up floor heat upstairs, would alleviate all these symptoms and heat up the cold kitchen floor. 

    But there are probably a lot of things on the wish list before that.
  • exqheat
    exqheat Member Posts: 185
    Is the outdoor reset adjusted to give you the optimum temperature at the boiler for even comfort. If the thermostat is near the boiler and being satisfied as it satisfies that room, the last room is being left short. Indoor reset is explained on www.exqheat.com.
    John Cockerill Exquisite Heat www.exqheat.com Precisions boiler control from indoor reset.
  • Tonerlow
    Tonerlow Member Posts: 60
    @exqheat

    boiler downstairs in laundry room.  Thermostat upstairs in the main hallway. East side of house is kitchen/ living room. West side 3 bedrooms and 2 bathrooms. So the thermostat is satisfied basically when the kitchen/living room /entry are heated. 
    Also large south facing window in the living room. Further complicating the evenness of heating on sunny cold days. I would love to pipe the upstairs in 2 in floor zones eventually. And split it east/west. 
  • hot_rod
    hot_rod Member Posts: 22,121
    Do you have the manual, if not download one. I think that boiler needs to be piped with a li loss header item primary secondary. The manual will show the piping options
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • Tonerlow
    Tonerlow Member Posts: 60
    @hot_rod Yes VEISSMANN strongly suggests a LLH or closely spaced “T”s. Have raised this point to my contractor. He is proving himself difficult to work with. “Did not quote you this job with a LLH”
    But the manual suggest using one, and I was relying on my contractor to know what he was doing during system design. If I could go back in time I would use the out of town contractor who quoted the same price.  I think I’m on my own to optimize this system at this point unless we pursue legal action at some point. 
  • hot_rod
    hot_rod Member Posts: 22,121
    That is a tough spot to be in. For that boiler to operate happily, and live a long life it needs a repipe.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 7,832
    Is it just me? Jamie. Bob? No one has mentioned the 3/8" flare zone valves! That looks like a huge restriction. I understand the valve body has only a 3/8" diameter hole in it from that valve all the way up to the 1" copper sweat zone valve. I need to look at the numbers on that actual 3/8" flare valve body, but @Tonerlow is not getting 4 GPM to either zone. The question is what amount of radiation (lineal ft.) is getting the heat from that zone valve. I can see the temperature dropping thru those zones as the heated water arrives at the last 15 feet of each loop.


    Edward F Young. Retired HVAC ContractorSpecialized in Residential Oil Burner and Hydronics
  • Tonerlow
    Tonerlow Member Posts: 60
    edited February 2023
    @EdTheHeaterMan just what I was wondering about. The restricted orifice of the zone valve vs the bypass set up how it is. 

    This really should be repiped with a LLH and eliminate the zone valves, put a thermostat controlled pump on each zone, boiler pump supplies LLH, and DHW supply pump. ???? 

    I might have to threaten legal action on my contractor to get this rectified. 

    On another note, the other plumber who quoted was going to install a 100-w 125BH boiler rather than the 200-w. I wonder which would have been more suitable to this application? (Also he was going to do 53g water tank instead of 42g) Kicking myself that I gave the local guy the job. 
     Hindsight.


  • Jamie Hall
    Jamie Hall Member Posts: 23,276
    Honestly, @EBEBRATT-Ed , there seems to be enough other odd things going on that I wasn't paying much attention to those flare fittings -- other than muttering to myself that they shouldn't be there.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • Tonerlow
    Tonerlow Member Posts: 60
    @EBEBRATT-Ed @Jamie Hall the reason for those flare fittings being there is easy. They have been there since 1976. The plumber cut out the old boiler and stuck in a new one. Which is not designed to operate in the same fashion as an old High temp cast iron unit. 
  • hot_rod
    hot_rod Member Posts: 22,121
    I’d guess they are 1/2” valves2.5 or 3 Cv maybe
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 15,517
    The boiler isn't piped right as @hot_rod mentioned. The plumber should have put in the LLH. Since he didn't at least add the tee and another pump and make it primary sesondary with a balancing valve in each circuit to set the flow.

    The reason your getting noise is the ball valve and the bypass valve are too small for the flow when no zones are calling.

    High water velocity causes noise
  • Tonerlow
    Tonerlow Member Posts: 60
    edited February 2023
    @EBEBRATT-Ed Yes totally agree. And the fact that the ball valve must remain part way closed this creates a bunch of noisy turbulence. 

    I’m seeing the 200w B2HB 94 has a max flow rate of 6.4 GPM? Hoping like hell the Grundfos 26-99 is not causing too much flow over heat exchanger. They have a top rating of 33 GPM (with no head pressure mind you)

    Found a drawing similar to how this is piped, so I guess that is the plumbers out? AND according to this drawing, he has both pumps on the wrong side of the boiler? Shows heating circuit pump (E) on supply side, mine is on return side (again where it was on the old boiler and they didn’t bother to move anything) And then in big BOLD letters on this page it says DHW PUMP (F) MUST PUMP INTO THE BOILER and he has mine on the supply side! 
  • Tonerlow
    Tonerlow Member Posts: 60
    edited February 2023
    I think I would be fine with the system set up as is IF there were a way to have the pump cut out at the end of a heat call. Would need the zone valve to stay open, pump to run an additional 30 sec or so then cut out then the zone valve close. Plumber says VEISSMANN told him it can’t be done. Is there external controls available to accomplish this.

    Or could eliminate zone valves and have a thermostat controlled pump on each zone? 

    Then the bypass could be closed and all the noise gone. and assumably much more flow to the rads without the short cycling thru the bypass

    He did have it set up that way for some time, problem being that the boiler did not know a heat call had ended, the burner would only cut out when the flow sensor tripped it out. By this time it would be very close to FIXED HIGH LIMIT fault.(could hear kettling in the Heating coil)  And sometimes trip the boiler into lockout. 
  • GGross
    GGross Member Posts: 1,043
    edited February 2023
    If the 2 pumps in the picture are all you have, then the plumber has piped this boiler incorrectly for the application. No 2 ways about it, they need to re-pipe it, doesn't matter how they bid the job, if they are licensed and know what they are doing then they will know why they need to fix it.

    This application needs to be piped as primary/secondary, it does not matter that the install manual shows a direct pipe config, that is not a blanket diagram to be used in every scenario. those diagrams are meant to be examples only. The bottom line is that the boiler does not function correctly, and the reason for that is the improper piping.

  • Tonerlow
    Tonerlow Member Posts: 60
    @GGross Hello again

    What would you suggest if you were re-piping this setup? Add a pump for each zone and if those pumps are thermostat controlled the zone valves could be eliminated? Along with obviously insisting on the addition of the LLH

    When I last asked the plumber about this he said he did not quote with a LLH, then continued on to say that he added the bypass to eliminate the water hammer we were getting when the zone valves closed. Which was true at the time but as we have now discovered the bypass is being used instead of a LLH to maintain flow. Add to that the fact that the bypass did not eliminate the water hammer, ultimately I removed a spring off of each valve to allow then to close more slowly, solving the problem myself.
  • GGross
    GGross Member Posts: 1,043
    edited February 2023
    Piping with either a low loss header, or making a primary secondary system with close spaced tees would be fine. On the side of the piping with the zone valves the simplest thing to do would be to add a pump.
  • Tonerlow
    Tonerlow Member Posts: 60
    @ggross in a typical system set up is it necessary that the boiler pump runs constant or this pump can come off and on with the burner with proper coding ?
  • GGross
    GGross Member Posts: 1,043
    @Tonerlow

    Typical Viessmann method is to use utilize constant circulation with a supply sensor located generally inside the LLH, boiler wants to maintain that supply temp. However they did make a coding change which allowed for on/off traditional installation, which it looks like you are using since your screen has the semicircle instead of the house. The boiler pump may still keep running depending on outside temperature, but it will turn on/off a system pump wired to the 28/20 pump output. if the only thing that is needed is to start and stop the boiler pump then it could be wired to the boiler as a zone pump on 28/20, this terminal would need to be set as the pump for whichever zone circuit you are using, through the installation wizard. I do not recommend doing this personally but it could be attempted to see if the problem goes away. You will still potentially have flow issues that may manifest themselves through other problems
  • Tonerlow
    Tonerlow Member Posts: 60
    @GGross I believe this would have been the original setup, when we were having the F2 fault and high limit switch problems. I know they initially had some trouble with the comms between thermostats/pumps/boiler. Maybe all the while due to trying to avoid adding the 3rd pump to the system. 

    Sounds like I need to lean on the plumber pretty hard to buy me another pump and at least re pipe this with the closely spaced tees, preferably with a LLH 
    GGross
  • Tonerlow
    Tonerlow Member Posts: 60
    edited February 2023


    @GGross @EBEBRATT-Ed @hot_rod @Jamie Hall @EdTheHeaterMan

    I have taken a panoramic of the boiler piping, labelled what is located where. I am doubtful at this point of the plumber agreeing to install a LLH on his dime, and to be honest I can see how it could be a challenge based on the space remaining on this wall.

    I have attached 2 drawings, one with the piping as is and one with a primary/ secondary with closely spaced tees. This actually does not require very much re-piping. Does this system design look ok to you gents? How much space is required between the tees?

    I am hopeful I could talk my guy into as re-pipe this summer, really this looks to me like 2 hours of plumbing, wiring and cost of one more pump and then set up of controls and coding.

    Would appreciate any thoughts on this, and appreciate all of your time and expertise so far !

    Also would you eliminate the flare fittings on the zone valves while the system was drained?

    He is warning me of possible water hammer issues returning if we change the piping and eliminate the bypass. I am not sure about this and I'm guessing would be on my own expense to remedy it if it was a problem.

    Also for the rest of you here is GGross and mine first thread and discussion of all the issues we have had since install https://forum.heatinghelp.com/discussion/189827/veissmass-200w-high-limit-switch-problems#latest