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reset (33 Posts)
resetIm using a Caleffi boiler protection valve on a atmospheric hot waater boiler (cast iron), the circulator will be constant circulation with wwsd, I will be using a tekmar 256 for outdoor reset, will not be using tstat......apt building 12 families....question is since im using a BPV, can I disable the boiler mininum temp on the tekmar to allow for FULL outdoor reset?...thanks Paul S
In one word,No. You should never shut that boiler down below 140 degrees. If you do, the heat exchanger will rust away into a useless hunk of metal. For what you are trying to do, you have to do your reset via mixing outside of the boiler.
evenWith the caleffi boiler protection valve, wouldn't it protect the boiler from condensation, ? what can i use if i cannot use full reset with that valve in place?Paul SThis post was edited by an admin on December 22, 2013 10:08 PM.
I imagine you are tired ofhearing from me but I am only trying to help.
The Caleffi valve you are looking at has one job. That is to prevent cold water from entering the boiler. That is all it knows how to do. It will keep the boiler bypass open until the boiler reaches 130 to 140 degrees. Then it will start to open and allow the hot water to start flowing out to the system. But you already know this.
Here is what you don't know. To run constant circulation and wwsd with no thermostats involved, you are going to be running some low water temperatures a lot of the time. Down below a 100 deg.
Now, what do you suppose the Caleffi valve will do when it sees 100 degree water coming from the boiler? It will put it right back in the boiler because that is it's job and will always do it's job.
In a previous thread I gave you 2 options that will do exactly what you want to achieve. The best one for you is Tekmar 360 with a 4-way mix valve and operator. If you choose this I will tell you how to do it with only 1 circulator and without the extra primary-secondary they have shown in there manual. The boiler you have will allow you to do this.
It is expensive, I know. But we'll worth it. If you don't do that about the only thing you have left is to put in thermostats and zone the sucker.
BelieveMe , im never tired of hearing from any of you guys. Ok, so I will bget the tekmar 360 floating mix cintrol, with tekmar 721 4 way valve, and 741 actuator. Is that all I would need? Thsnks Paul S
the boiler pumpis this a single pump system, so the boiler pump circulates the boiler and all the building?
Here is a graphic of how a thermostatic valve works as a return protection, regardless of the brand, they all follow this MO.
It the temperature returning, falls below the valve setpoint that return port closes and the bypass will be open 100%. So all the flow from the boiler is diverted right back.
So the boiler will only run cold, or cool, until it heats itself up. A few, maybe 10 minutes?
The color of the lines is intended to show how the valve responds.
Some of the supply starts to flow to the system as soon as the return sees setpoint, 100% flows out and back to the boiler when the valve is setpoint plus the 18° differential.
he is a Excel form for calculating pressure drop through a valve. So for example in the third box, if you have a valve with a Cv of 14, and say for example you want to flow 24 gpm thru it, enter those two "knowns" and it shows you the pressure drop in psi and feet of head. so the pump needs to be able to move the GPM plus the pressure drop that the piping circuit presents.
Those are the essentials, yes.I personally include the indoor sensor with this package. It provides feedback to the 360 and allows it to automatically fine tune the reset curve so you are comfortable both on cloudy days and sunny days and windy days.
sensorTekmar 076 indoor sensor, and where should I put it, its a 12 family apt building, and no real way to get wiring above 1st floor and how do I pipe 4 way valve with just one pump? Would this drawing work ?Paul SThis post was edited by an admin on December 22, 2013 11:07 PM.
Just put it onthe first floor wherever you would put a thermostat. Central location. Not close to any alternate source of heat or where it would get hit by the sun.
Yes that drawing would work.I have attached a pic showing the proper piping diagram. Dis regard the indirect water heater since you don't have one. every thing else stays the same.
Put the system supply sensor downstream of the circulator. Put the boiler sensor on the supply pipe as close to the boiler as you can get and wrap it with insulation tucked in tight against the boiler jacket.
thanksThanks Harvey for all your help. Paul S
Nice drawing. However...During a draw for DHW I assume it takes the heating system off line with the 4 way valve to prioritize DHW, and if so, it is missing a critical but small component. See where the DHW supply branch tee comes off the boiler primary? Between that junction and the 4 way valve there needs to be a check valve flowing from L to R.
Now if your intent was to create a boiler bypass by not having a check valve there, then it will work really well, but it may take 2 times as long to recover a DHW load, and it may not even be able to handle the simultaneous load (draw) due to the bypass that would occur. Flow to the DHW tank would be parallel. Some of the return water coming back from the DHW tank would head back to the boiler for additional heat, and some of it would head back UP towards the 4 way valve, and mix with the hotter water coming from the boiler, lowering the supply temperature to the tanks coil.
I guarantee the boiler wouldn't condense when it is making DHW, but is that really a major consideration anyway? Another way of piping it would be to set the DHW takeoffs as a true secondary (closely spaced tees) on the boiler return. You'd still have to prioritize with the 4 way, but it would eliminate the head associated with the check valve, and it WOULD get hot QUICKER.
Is that a Siggy original? Or one built using his program? If it is a Siggy original, and it wasn't his intention to create a bypass, you might let him know of the discontinuity in his drawing as a matter of respect.
Remember, water is like my ex brother in law. Wet, lazy and stupid. It WILL follow the path of least resistance, which is not necessarily the direction you THOUGHT it was going to flow.
Think like water grasshopper… :-)
Lastly, I have had many opportunities to look at the fireside of many cast iron boilers, all with different methodologies of boiler protection, and have found that those that utilize the thermostatic anti condensing valve are without a doubt THE cleanest I've ever seen. In fact, they looked brand spanking new. NO signs of condensate corrosion at ALL. And that includes P/S piping, VS Injection, solid state controls with VSI/P-S… You name it, I've seen it, and the boiler protection valves that Hot Rod is showing work the best. Don't forget to incorporate a bypass around the BPV on the return or purging will become very difficult, depending upon how you set your purge(s) up.Makes it virtually impossible to do a cold fill and purge.
MEIt's not so much a case of "You got what you paid for", as it is a matter of "You DIDN'T get what you DIDN'T pay for, and you're NOT going to get what you thought you were in the way of comfort". Borrowed from Heatboy.This post was edited by an admin on December 23, 2013 9:00 AM.
Hey MarkI try to think like a grasshopper every day ;-)
This is a Siggy original. I for one, am not about to critique the Master. Even if he was wrong I wouldn't point it out because somehow I would end up a dumbass. lol
Take a closer look Mark. The piping size changes right after the DHW tees. You still might get some reverse flow but I tend to think it would work.
But at any rate this man has no DHW so he can just eliminate this whole business.
Also what he is trying to accomplish is this. Constant circulation, ODR, no indoor thermostat and WWSD.
The thermostatic BPV won't work very well with this business unless he adds another circulator.
Harv...I hear what it is that you are saying, but you have to remember that there are a LOT of people viewing this thread, and one of them may decide that the drawing you presented would work on his system with DHW. I've invited John to come by and comment if he is interested.
We ALWAYS need to be cognizant of that as a real possibility,even though it wasn't our intention. Nothing serious would come of this, other than slow recovery and poor output to a large DHW load. But as we have seen with the thread over in Radiant, shortages of DHW can be exasperating…
Thanks for your continued participation.I enjoy reading your down to earth, common sense posts.
MEIt's not so much a case of "You got what you paid for", as it is a matter of "You DIDN'T get what you DIDN'T pay for, and you're NOT going to get what you thought you were in the way of comfort". Borrowed from Heatboy.This post was edited by an admin on December 23, 2013 11:19 AM.
Confirmed...I communicated with Siggy, and he said it does look like one of his drawings, but with thousands and thousands of them out there, who knows where it came from, but he confirmed that in order for it to work as designed, you would have to have a check valve where I said it should go.
By the by, the one pump 4 way system has always been known to me as a European design. The Tekmar book shows 2 pumps for Americanized boilers. One for the loop, and one for the boiler. Not really sure why the Euro's would go that route other than parasitic power consumption, but I've never thought it was a good idea to fire a hydronic boiler without having flow through the vessel. Obviously, that statement doesn't stand for steam boilers….
MEIt's not so much a case of "You got what you paid for", as it is a matter of "You DIDN'T get what you DIDN'T pay for, and you're NOT going to get what you thought you were in the way of comfort". Borrowed from Heatboy.This post was edited by an admin on December 23, 2013 6:07 PM.
Thanks for the followup Mark. Once again I sit corrected and find myself agreeing;-)
Check valve is necessary, yes. Exactly where Mark said it should go. Between the DHW supply tee and the 4-way valve. A swing check should be used and should be piped horizontally. A spring loaded check valve should not be used. The 4-way valve has to induce flow though the boiler and does not like much resistance.
A typical 4-way valve installation with a modern cast iron boiler should be piped according to the manual's diagram. With both Taco and Tekmar, this would consist of a primary boiler loop and a boiler pump. 2 closely spaced tees coming off the primary loop going to the "boiler side" supply and return ports on the 4-way valve. This will provide greater temperature reading accuracy on the boiler loop and in the case of the Tekmar, better boiler control.
The diagram I posted was specifically intended for Paul s
I for myself prefer to use the 4-way valve with a single pump (as depicted in the diagram) when converting an old gravity flow system to circulation.
Mark, now I have carpal tonal in my fingers ;-) I am picking up what you are throwing down though. People don't know what I'm thinking regardless how hard I type. If only I could articulate the way Dan does.
guysWhen would you use the boiler pump with the 4way valve?on a boiler with high presure drop? Paul S
Yes, or...a low mass flow critical boiler, like a copper fin tube design, OR if the manufacturer requires it.
Don't want to void any warranties…
resetI will be using the Tekmar 360 setup with the 4 way valve, but just for my knowledge would i be able to use the boiler protection valve with some sort of hydraulic seperation and provide FULL outdoor reset to the main system with the main(system) pump on constant circulation, like in the drawing i drew below? thanks .....Merry Christmas.... to all Paul SThis post was edited by an admin on December 25, 2013 11:44 AM.
anyoneAnyone have any insight? Paul S
That will work great...I'd also suggest you consider non electric TRV's to shut those zones down that WILL over heat.
It is virtually impossible to find the utmost "ideal" conditions whereby constant circ doesn't create conditions of discomfort due to over temp. Park you thermostat in the worst case scenario room (top floor, outside corner for example) and then let the non electric TRV's do their thing to send the heat where it needs to be.
Don't forget a bypass for fill and purge around the BPV.
Many different ways to set up a purge, just make sure you incorporate it into your designs.
Now, quit frettin' over your future heating system and go enjoy some family life :-) This will wait.
i wasIntending on not using a thermostat, its a apt building and theres no real common area where i can put one, and TRV'S are out of question due to type of system, series loop system with rads, i was just gonna use full outdoor reset with tekmar 360 and 4way valve. thanks Paul S
Full outdoor reset...Hi Paul,
I am having a hard time with the term "full outdoor reset". I think at the top of the thread you said you want to disable the boiler minimum setting on the Tekmar control. I don't see what you will gain? You still have to produce ~130F water in your cast iron boiler.
Even with the nice Caleffi BPV or the budget EBSE valve like I used, you can't tell the boiler you only want 100F water, which a 256 WILL call for on a 30 degree day without the minimum setting enabled.
Maybe I'm misunderstanding you.
I'm posting a picture of my boiler redo that I'm still tinkering with. It looks a lot like your last drawing - P/S with a BPV. Cast iron boiler. Tekmar 256. Constant circulation. Bell & Gosset Vario EcoCirc pumps (1 Auto and 1 Vario) But I piped it as a 2 pipe reverse return, so I've used TRV's.
Works very nice :-) The BPV is a bit of a challenge, though. Like Hot Rod said in another thread, if you use a 140F element, it is out of sync with the ODR. Need a 120F element to work well. It will just match reset device.
I'm a hack, so no offense if I've said something wrong.
resetIf the boiler sensor is on the supply pipe of the distribution system and during FULL reset if it wants 100f water temp at that point, the boiler would have to have at least 130f water before the BPV would start closing it's bypass allowing water to flow to those closely spaced tees that lead to the system. I think you are referring to if I wasn't using some sort of hydraulic separation, for example using one pump with the BPV and the Tekmar,if the Tekmar wanted 100f water the BPV wouldn't allow water to flow through the system. Let me know if your not following.thanks Paul S
This...Merry Christmas, Paul.
This is what I was referring to:
"question is since im using a BPV, can I disable the boiler mininum temp on the tekmar to allow for FULL outdoor reset?...thanks Paul S"
I don't think you can. Make your primary loop as compact as possible and set the minimum temp at 140 in your ODR and let your secondary loop take what it needs from the loop. Use some sort of wireless t-stats to turn on your secondary pump.
I'm probably in over my head here, so I'll just leave it at that.
anyoneCorrect me if im wrong, if im doing constant circulation w/o tstat, and i set the tekmar mininum temp at 140f, wouldnt it overheat building? so like the pic i drew above, i provided hydraulic separation between the boiler loop and the distribution system. If i provide FULL outdoor reset to the distribution system, and it wants lets say 110f water. the hot water (somewhere above 130F)will not get there until the boiler is protected, once the boiler is protected the BPV will slowly close the bypass sending water toward the closely spaced tee's.....Paul SThis post was edited by an admin on December 25, 2013 10:40 PM.
Paul, did you try this yet?Let me know. If I have time tomorrow afternoon I'll move my sensor and try out what you are suggesting if you would like.
VSIMPaul, have you considered variable speed injection mixing? If you added one more pump on the system side it would work for full outdoor reset. On your second drawing, if you added a system loop and pump connecting to the top of your closely spaced tees it would work perfectly. The pump on the closely spaced tees would inject water from the the boiler loop into the system loop as needed to maintain whatever temp is required. Off the top of my head, I cannot remember which Tekmar controller it would need, but that is easy enough to find out. It's a great way to provide boiler protection and full outdoor reset.
resetI believe would need the tekmar 356, i already used the tekmar 360 w/ 4way valve. would i be able to use the variable speed pumping with the BPV?Or its not needed because the variable speed controller has boiler protection? But in my drawing above wouldnt i be able to use it too, with full outdoor reset? thanks Paul S
Full outdoor resetPaul, with your drawing above, you will not be able to get supply water that is below 130 degrees. With the 356 and no BPV you can get supply water as low or high in temp as you want it and still maintain boiler protection as the controller does that for you. As well, there are no expensive valves to maintain, control or replace in the future.
Sorry it took so long to respond, but I was out of town for the holidays.
RobI drew a pic below if i would be using the injection pumping setup with the tekmar 356. i have a few questions though, what size pipe do i use for the injection risers?system is a basic direct return two pipe system with radiators connected in series from each branch circuit, i know its not right. i really dont know what TD to use to size my injection risers, andwith this setup would i be able to have the system pump on constant circulation with WWSD and what can i use as a mixing demand that the control requires? i donot want to use tstat in this case, would i be able to constant power the mixing demand and have the outdoor sensor setup with WWSD? thanks Paul SThis post was edited by an admin on January 2, 2014 9:22 PM.
Exp & SepJust curious, wouldn't the microbubble absorber work better on the system side? Granted it will be larger and cost more.:NYplumber:
Tekmar 356Paul, with the 356 you can run constant circulation and operate without a thermostat. If you wanted to have indoor feedback you could use the 361 control. for sizing the mixing legs and pump use this link. http://tekmarcontrols.com/images/_literature/e0021_06.pdf Hope this helps.
As well, in your drawing, the supply and return of the mixing legs should be reversed.
RobThis post was edited by an admin on January 4, 2014 1:13 PM.