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Do I use a control here?

Chuck_36
Chuck_36 Member Posts: 42
I have a one zone conversion with a bypass for boiler protection. It is insufficient. The boiler will not rise to the safe temp. to satisfy the thermostat.

If I put a thermic valve in place of the "T" of the bypass's return end, and "T" off the bypass adding a second circulator for the radiators, should I use a control to turn the second circulator on and off at a settable temp?

If so what kind of control?

Comments

  • CMadatMe
    CMadatMe Member Posts: 3,086
    edited March 2011
    From What

    You have a one zone conversion from what? If a by-pass was used how was it piped and what regulates the flow out to the system and through the bypass? Can you post a pic or at a min a diagram of how the boiler is piped?
    "The bitter taste of a poor installation remains much longer than the sweet taste of the lowest price."
  • Chuck_36
    Chuck_36 Member Posts: 42
    Control?

    It began with a coal fired boiler, then converted to fuel oil with a circulator, now it is natural gas with a Burnham 204.  The radiators and mains have remained the same. The bypass is 1 1/4" CI from the 1 1/4" vertical supply across to the 1 1/4" vertical return with a Globe valve in the middle of the by-pass. The circulator is below the bypass on the return leg pushing into the boiler. On the supply , above the by-pass is a Globe valve used to throttle the flow to move more water through the by-pass. The set up is as Burnham showed in the installation manual. Because of so much water circulating, and the house is well insulated, the boiler will max out at 120F on the coldest nights and be lower otherwise and satisfy the thermostate. I want to use a thermic valve and a separate loop for the radiators, leaving the present circulator in it's position.
  • bill_105
    bill_105 Member Posts: 429
    edited March 2011
    Burnham 204

    Chuck - That's a real simple boiler. And the diagram in the instructions is rather crude. Pictures would help. Why is the temp of the boiler so low? I wouldn't think pumping issues
  • CMadatMe
    CMadatMe Member Posts: 3,086
    Circulator Placement

    Circ needs to be on the supply after the exp tank for starters. Please post some pics.
    "The bitter taste of a poor installation remains much longer than the sweet taste of the lowest price."
  • Chuck_36
    Chuck_36 Member Posts: 42
    Control on Burnham

    I don't know how to do diagrams. From the 204's output I have a vertical pipe with a "T" for the by-pass going leftward towards the "T" on the return. The return is vertical, and the circulator is on the return pulling down to the boiler. That is common here in Boston, I do believe. I have a globe valve in the bypass and another one in the supply pipe just above the "T" of the bypass. I have about 100 gallons of water to circulate and it acts like a heat sink. I have been told the boiler is too small, yet it is rated way over the needs of the apartment. The installer sized it to the radiation but perhaps not large enough. Either way, a 140F thermic valve in place of the return "T" is one suggestion. The other which I prefer, is the thermic valve at the return "T" and reposition the supply close to the valve "T'd" off the bypass with it's own circulator pumping away. That option overcomes any irregularities in flow to the radiators from the action of the thermic valve. The existing circ., pumping down, remains and the second one pumps away. I need to know if the two operate in tandem off the thermostat or is a special control needed to run them independently? That is about it.
  • Chuck_36
    Chuck_36 Member Posts: 42
    Control on circulators

    I understand. Yet 1/2 the installers, including mine, put it in pulling down. If I had 10 installers 5 would say pull down and 5 would say pump away. I appreciate your comment.

    Even the literature for a system by-pass will say either way will do. One thing, it is noisy. In my case I think you are right.
  • icesailor
    icesailor Member Posts: 7,265
    Circulator Placement:

    HVAC,

    I have in my hot little hand, a book I got at a Taco/Heatway seminar that Dan H was at in the '80's. Taco Guide For Hydronic Engineers. Forced Circulation Hot Water Heating Systems. 3rd edition. Almost every piping diagram shows the circulator on the return side of the boiler.

    It was well understood by the dead and soon to be dead, hydro guys, that the circulators did better on the returns because the shaft seals couldn't take the hot water and started leaking when on the supply side. This seems to have been solved with wet rotor circulators.

    It is highly unusual in New England to see an old boiler that the circulator isn't on the return. Package boilers ALWAYS came with the circulators on the return.

    I've tried to force myself to put circulators on the supply and then, I go study up on doing a Veissmann Vitodens and there, in plain sight, put the boiler circulator on the return, pumping into the boiler. Just what I have always done. Pump into the boiler. I've never had all this air problems that every one seems to have and I don't even use air vents on my radiation. I purge it once and never touch it again. No over pumping from over sized circulators that have to overcome bad piping practices.

    Last night when flying home from work, I watched the ferry backing out of the slip. The water was white around the boat from prop cavitation. Just like in a heating system.
  • Chuck_36
    Chuck_36 Member Posts: 42
    Control for two circulators

    My system goes snap , crackle and pop whenever it comes on. My bedroom is closest to the boiler and I can hear it best when, on a cold night, the system is turning on. As my main purpose is low boiler temp, I have put the noise as a secondary concern. If anyone wants to look at the January 11, 2011, Gas Heating section, the entry " Two Zones...." shows a diagram with two alternative piping arrangements. That diagram is based on the description of my piping to Gordon who drew them in response. I can assume since he showed no other controls in the P/S view, that the two circulators run in tandem. I need confirmation of that from someone.

    Will someone kindly confirm to me one way or the other about the two circulators?
  • CMadatMe
    CMadatMe Member Posts: 3,086
    edited March 2011
    Vitodens Circ Placement

    Ice,

    You will also see in the Viessmann piping diagram that the exp tank and feed are  below it. We are still pumping away from the point of no pressure change. Circulators were put on the returns because it was easier for boiler mfg to crate them and they could also get more on a truck is they packaged them that way. If you look at the diagram in the Series 2 installation manual it state the the pump on the supply is the preferred spot.
    "The bitter taste of a poor installation remains much longer than the sweet taste of the lowest price."
  • Chuck_36
    Chuck_36 Member Posts: 42
    Pic of system

    If you look on Jan. 11, 2011, you will see what I am wanting to do. Gordon showed pics of his suggestions and he asked me to describe the piping before hand. The two circulator solution is what I prefer.  I want to get feedback if the circulators will operate on and off as a pair, controlled by my single thermostat. The plumber I asked to do the job says a control is needed, making each a separate zone. P/S piping, I think for my case, doesn't use a control for the circulators. I could have a control installed which will turn on the second circulator only after it senses 140F in the boler. That may be workable but not really necessary in my case. I want the second circ. to provide more uniform flow in the radiators.  I think that flow would be affected by adding the thermic valve in the bypass loop and that is what I want to overcome with the second circ. option. As you can see in the left diagram, the thermic valve alone is suggested as an optional solution and gets supported by another's experience. I can use either way and see what results I get next winter. I have just finished my third winter. Each winter has had some change to the piping which has made no difference in the system temp. This winter, a plumber demonstrated the affect of so much water and showed me that my boiler is too small. It is too small for the water volume but too large for the heat loss in the house. I am trying to compensate without replacing the boiler.
  • icesailor
    icesailor Member Posts: 7,265
    Vitodens Circulator Placement:

    HVHEHCCA,

    I have in my hot big hand, the manuals that came with a Vitodens100-W I am installing. On the bottom of the page is # 5368 828 v1.2  11/2009. On pages 28, 29, 30, and 31, they all show the circulator piping directly into the return side of the boiler. The expansion tank is shown on the supply side. Regardless if you use closely spaced tees or their low loss header. Which they strongly suggest using instead of closely spaced tees.

    As far as circulator locations, ceramic faced seals on circulators had a very high failure rate when put on supplies. The hot water acted on them lust like they do on those $hitty red rubber circulator gaskets so many use instead of the black square O-ring that the manufacturers send to be used with their equipment, When put on the return, where the water was usually 20 degrees cooler, they lasted a lot longer. Wet rotor cartridge circulators solved this problem. Not the flange leaking problem though. I switched to Wilo because of that nice, fat black round gasket they use. There is no way you can use a junk red rubber one on it
  • icesailor
    icesailor Member Posts: 7,265
    I don't quite understand:

    I don't quite understand what your problem is. You have a boiler that is too big BTU wise? But you can't get the radiators hot enough to heat the building? And you will solve this with a thermostatic valve?

    What am I missing?

    If you have a lot of radiators, but they don't equal the output of the boiler, something is wrong that won't be solved with a thermostatic valve. If you have large supply and return pipes, and you have excessive heat loss from the piping, insulate the pipes.

    I haven't figured out what your problem is. 
  • Chuck_36
    Chuck_36 Member Posts: 42
    Boiler size

    A plumber constrained the water flow in the supply using the valve on it. I observed the boiler temp rise more than it ever had before. Then he opened the valve and restored the flow and the boiler dropped in temperature immediately. He said my boiler was too small for the water volume. The water acts like a heat sink.

          The heat loss calculations for the apartment indicate the losses at almost half of the rated output of the Burnham 204 (96K IN, 70K out). Calculated losses, some  considered high because the UNICO program was used, are close to 50K, without allowance for piping.

           That is why I say the boiler is too large for the heat loss and too small for the water volume.

           The apartment heats up at a low radiator temperature (120F Max) only on the coolest nights. Otherwise it is lower. As low as 90F in Spring and fall.  The heat is least comfortable at the farthest point in the system, my living room. That is where the thermostat is, on the inside wall. I suspect the heat is layering, heating the air from the ceiling down to the height of the thermostat. Below that is uncomfortable.

            The boiler should run in it's safe temp. I have always had a system bypass like the manual called for. You know the Burnham booklet is shoddy. They confuse readers by using the term "boiler bypass" (small "B") when speaking of boiler protection and the diagram correctly shows a system bypass.



          

     
  • icesailor
    icesailor Member Posts: 7,265
    Boiler size:

    I think that someone overthought this.

    Have you tried just leaving the bypass valve opened? (or closed) If the boiler has enough nuts to heat the building, it will do it. The problem with what you are doing is that you restrict the GPM flow from the boiler to the system. This is Hydronic Heating 101. Turn the high limit to 160. Open the bypass valve all the way (or close it) so that ALL the supply water goess into the system and all the return water returns to the boiler. If after a while, does the water get hot going into the system? How hot is it? If it is say, 150 degrees, how hot is it coming back? 130 degrees? You have a perfectly designed or whatever system. If the water doesn't get as hot in the farthest places, the flow may be too slow. Let it run until the whole system gets hot.

    Make sure the boiler is big enough before you get nuts with valves.

    What part of what I said don't you understand or what part of what you said did I miss?
  • Chuck_36
    Chuck_36 Member Posts: 42
    Thermostatic valve

          If I use a Danfoss 140F valve in the bypass loop, it will open and close with what it senses from the bypass flow and the return flow from the radiators and be fully open at 140F or more; then the circulator pulling to the boiler will be feeding the boiler 140F water.  The valve is piped on the return end of the bypass in place of the "T" which is there now.

          If I throttle down the supply flow, more water will go to the bypass, as now. I am concerned what the time taken to reach 140F will be; and before that time, will the thermostat be satisfied?

          That is one reason I want to control the supply flow with a second circ. I will use another Grundfos 15-58 which has three speed settings. That will give me more ability to "Tune" if necessary.

         The thermic valve was common in the days of coal fired boilers, I have been told.

          It is supposed to get the boiler temp into the "Safe" temperature range.

          It could impact supply flow to the radiators or affect the room temp mentioned before.

          Because of that, a P/S loop was advised with a 2nd circ.

          I want to know if the second circ. is wired to turn on and off with the first circ. That is what I want to know.
  • CMadatMe
    CMadatMe Member Posts: 3,086
    edited March 2011
    Sorry Not Correct

    Supply is on the left, return is on the right on the boiler. Install manual attached. Exp Tank, Feed and pump are clearly on the return. Page 29 and 30. If your flow rates are more then 1.7gpm or and less than 6.2gpm then the pump would be on the supply as you wouldn't be pri/sec or using a LLH. If you installed a presuree by-pass then the pump would have to be moved to the return. The pump would be then pumping away from the point of no pressure change and through the boiler. I attached the current install manual and the previous version. Same thing..
    "The bitter taste of a poor installation remains much longer than the sweet taste of the lowest price."
  • Chuck_36
    Chuck_36 Member Posts: 42
    The bypass

          The bypass has been fully opened for 3 winters now and I have tried to steer the supply temp with a throttle valve on the supply. Trying to keep as much water circulating at the boiler and getting enough to the radiators.

           I have never touched the upper limit switch. Why bother? It is set at 180F from the factory. I could only dream.

            Once, the gas company came at my request the first year. They shut the flow to the boiler and it shot right up to the 180F control limit and shut off. That satisfied them that the boiler controls were working. Then they left.

             I have used the full closed bypass and full open supply. It will satisfy the house at a lower temp. 10F lower.

             Return temp? 90/100F on the coldest days, down to 80F. I have thermostats on both supply and return positioned above and below the bypass. I do not stand there day and night, but when I am in the cellar, I will observe the stsem, write down readings, when I hear it turn on.

              It runs cool.

              Too cool.

               One installer who bid the job, wanted to install a Burnham 205 or 206. I could not believe what I heard. (I knew the apartment's heat losses)

               But I did not appreciate the impact of my water volume on the new small boilers.

               He was right.

               I could rip out my radiators and install baseboard and my problems go away.

               I could not afford it then and less so now.

               I can't afford a bigger boiler either.



            

             
  • Chuck_36
    Chuck_36 Member Posts: 42
    Typical cycle

    The system just ran for a few minutes; reached 110F supply and 80F return (before the bypass) then the thermostat was satisfied and shut off the system.  After the bypass the boiler saw 100F. The outside temp is 44F. This is how the system usually runs.

    I have sufficient radiator capacity to obtain 62625BTU if I had 170F water in them. AT 120F water I obtain 20875BTU.  That is enough to be comfortable in most rooms except the living room as I described, but the system turns on and off a lot more when the outside temp goes down in the evening.

    The boiler is not operating at a safe temp. and is condensing, or should be.
  • icesailor
    icesailor Member Posts: 7,265
    Controls:

    Years ago, I did a couple of jobs that used a Honeywell 3 way valve to keep the boiler water hot to run a big tank-less heater, The three way valve was run by a outdoor sensor and an analog Allen Bradley controller. It only had one circulator. It was a B&G P-3 high velocity circulator.

    I can't look at the install because I worked on it in 1965 and I know it was modified with a boiler replacement. I hate to think how it is now. But in thinking about it, the circulator must have been in the heating loop and the water circulated through the heating loop. It wasn't a four way valve, it was a three way valve. As heat was needed, it diverted more flow through the boiler. It modulated to keep the system water at the temperature that the outdoor sensor wanted.

    I have looked for this valve for years. I would put it in oil fired systems in a moment. You could run system temperatures at whatever you needed and keep the boiler water at 140 where it doesn't condense. That's what you need. I have to think more on the circulator situation. It was done with one circulator.
  • Chuck_36
    Chuck_36 Member Posts: 42
    Three way or four way valve

    Thanks for your comments. If you look at January 11th 2011, in this Gas Heating section, you will see the sketched suggestions from Gordon. I only want to know about the two circulator set up. Should they run on and off together or be controlled separately? I have the valves. I can get the circulators. My plumber will install them. 
  • Techman
    Techman Member Posts: 2,144
    Chuck

    Did you say ,the farthest and coldest room is the living room ?And the thermostat is in the living room ?And the t'stat is shutting the boiler off  before the system return temp rises?
  • Chuck_36
    Chuck_36 Member Posts: 42
    Front Room

         Yes. The front room has the largest amount of windows and the front door, and has a northeast exposure. But windows are new, door well sealed and walls-blown insulation.

          The least comfortable time is evening when sitting.

           I sense that the heat, with low temp radiators, is layering from the ceiling downward and when it reaches the thermostat satisfies the thermostat and shuts off the system.

           A seated person is below the thermostat and in the least comfortable zone.      

           As I sit closest to the thermostat, I hear it switch on and off. It switches more frequently as the temperature of the outside air goes down. It is properly located on an inside wall, and calibrated for my type of heat.

           On paper, I need 140F to 150F radiator temp to meet the rooms heat losses.

            I get 120F at best.

            I also suspect that I burn more gas than I should because the low temperatures turn the system on more frequently to satisfy the thermostat.

            The return temperature, at this time of year, when the outside air is 40F in Boston, the thermostat will be satisfied when the boiler puts out 100/110F and the return is 80F.  

            That is how it works, regardless of by-pass or not, or whether I set up a system or a boiler by-pass. I have tried each arrangement each winter since installation three winters ago. Initial installation had essentially no bypass. (1/2" Cu pipe. who knew?).

          An "Old timer" showed me that my boiler was too small to handle the water volume in the mains and the radiators. That came as an unwelcome surprise, but made sense.

          I am nibbling at the edges of this.

          I can't afford new boilers, the gas company has no interest, so I am willing to nibble at this more in order to raise the radiator and boiler temperature. I like the P/S approach and need to know how to wire the second circulator and/or  if I need a separate control between the two of them.
  • Techman
    Techman Member Posts: 2,144
    Chuck

    Why don't you raise the setting of the t'stat ?The colder it gets outside the longer each on cycle should be. What t'stat do you have ?
  • Techman
    Techman Member Posts: 2,144
    Low Temp Rads?

    140-150 is not "low temp rads".It is lower than the 180* of baseboard but not as low as low can go.
  • Chuck_36
    Chuck_36 Member Posts: 42
    Thermostat

    It is a Honeywell digital about 5 years old. Simple set point no program for days. I could do that but I have raised it 4F to 5F to feel any difference and that is not what I am trying to accomplish here. That room has been comfortable set at 69 to 70 with the previous oil burner. I could not have believed that I would have to make those kinds of changes when I converted to Natural Gas heat. The closer I looked the clearer it was that the boiler does not get up to temperature in the safe zone when I have the thermostat set at 70F. I have no margin to work with. 
  • Chuck_36
    Chuck_36 Member Posts: 42
    140F to 150F

             I would expect a properly running system would provide me with the ability to raise and lower the temperature and have the boiler respond. The EDR and BTU numbers work out to that range.

            I ran the boiler for 3 hours when new and when I suspected something wrong. After 3 hours continuos running time the supply temperature was 165F,  the return 160F and the room 80F.

             After 2.5 hrs. run time, the supply was 145F, the return 138F and the room was 75F.

             I don't know what those temperatures mean, maybe you can tell me.
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