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Closely spaced tees and other precepts
S Ebels
Member Posts: 2,322
The piping is wrong and will not work as pictured. You have nothing in the system to cause flow in the low temp loops. You would need a circ for each loop if installed as shown. The circ shoud be located so that it is pumping away from the mixing valve.
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Comments
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And multiple temp heating
I'm not a pro heating person. I am a builder, trying to take baby steps toward understanding a heating package we'll have done.
First, will someone please explain the need for the closely spaced tees, when doing supply and return of central heating circuits off the boiler's primary circuit?
Secondly, and this is about heating with different temp requirements per circuit, would we have a pair of closely spaced tees for each of our circuits?
We're going to use a small mod-con.
We've a scheme with panel radiators heating one floor, with 180F needed at max heatloss. That's one zone. There will be two additional zones, both inslab radiant, one fed with higher temp than the other because of the floor coverings. Those two radiant zones will each be done with manual mixdown and zone valves.
Would we thus have three different sets of closely spaced tees?0 -
For individual loops the tees should be no farther than 6" apart. Otherwise you have a pressure differential and you'll find the loop "leaking" heat when it's not called for. Be sure to place the supply tee in the primary loop before the return.0 -
Yes
You will need three sets of closely spaced tees for the load segments. The first set of take offs should be for the high temp panel rads, the second for the high load radiant, and the third for the lower temp radiant. Don't forget to also place your boiler tees in a close spaced (no more than 12") configuration. Pump away from the point of no pressure change (expansion tank) and I personally would use circulator pumps in lieu of the zone valves.0 -
Thanks very much. If you would kindly do so, take a look at the attached schematic, which shows the three heating circuits coming off a primary loop.
The radiator loop has its own circulator, but the two radiant loops have the zone valves you recommend against.
If doing a circulator for each of those two radiant loops, does the circulator come before the mixing, or after?0 -
What Don Said
What you are doing in that case is running "series" tees whereby the upstream (first-served) have benefit of the hottest water. This leaves the downstream cooler needs with less mix-down to do.
You could also work these in parallel so that they all see the same starting temperature but that is more work and no real benefit.
In series is simpler and the right thing to do. And you would appreciate this: It Costs Less
"If you do not know the answer, say, "I do not know the answer", and you will be correct!"
-Ernie White, my Dad0 -
Circulator after the Mixing Valve
In your diagram, Gene, with one circulator, the mixing valve will open and allow the supply to go right into the return. See ya! Nothing of consequence will go to the tubing.
Picture this: With a mixing valve, it has to be upstream of the circulator because it is pulling from two sources- the primary hot water and the return from that sub-zone.
With such a valve downstream of the circulator, it can only divert; like a traffic cop, the water can only go to the side or straight. If all goes straight, nothing goes to the return. That zone sees whatever water enters the circulator and whatever is not needed goes to the return. Nothing is gained. When diverted, there is no incentive to go straight through all of that tubing.
Make sense?"If you do not know the answer, say, "I do not know the answer", and you will be correct!"
-Ernie White, my Dad0 -
Lessons learned (thanks H.R. And HB)
Cast in stone, at the beginning of all our radiant books and drawings.." Always pump AWAY from the mixing device!!!".
I've had my share of screw ups, and will openly admit it, because I learned from them. One diagram I looked at , AND questioned, was from Oventrop/Viega. I was soon turned onto the fact that "Mixing Valves" and "Diverting Valves" have different needs. Deciding which to use is now the quest for each and every job.
Facts have been given to you about your situation. Use them. Chris0 -
Howzis?
My new schematic is attached here, showing the three different heating loops, each with its own circulator.
The mixing for the cooler radiant loops is shown, and circulators are positioned downstream of the mix. Does this look correct?
If you know about controls, what will outdoor reset control bring to the equation for control of the boiler, and then what will a single tstat for the entire area heated by the rads do? I am told by someone, I cannot remember who, that it is a good idea to have that one tstat, set high, as the means of shutting down the loop (turning off its circulator).0 -
Im not a pro
but doesnt the supply and returns on your radiant loops need to be reversed according to the flow in the main boiler loop? Like you have it in the panel loop?
And maybe a pro could chime in here but is there a issue with two lower temp zones being placed in the boiler loop beside each other? Wouldnt the first zone have hotter boiler loop water to mix with?
I have a main boiler loop and a low temp radiant zone just as you are trying to design in my house. Can take a few pics and post if you want.
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I think you are getting it.
Yup. Absent the details you did not show for clarity, the concept matches what we have been talking about.
The only suggestion I might have is regarding the primary loop. Some boilers have a high enough pressure drop that you want to pump into them rather than from them. You PONPC (expansion tank connection point) principle still applies of course.
Edit: The point below made by DC about reversing the take-off order of supply and return is spot on- I missed that. Good catch, DC.
Otherwise, looks good to me."If you do not know the answer, say, "I do not know the answer", and you will be correct!"
-Ernie White, my Dad0 -
Although...
DC's comment makes sense, with the mixing devices, it ain't such a big deal. You're going to be pumping 180° water through the primary loop anyway, at design temp.
I like the pumps vs. the zone valves in the design. The primary pump can only handle so much, and this assures that the flow will be going where it's needed.(and diverted/bypassed when NOT!)I also like the PDBV...our savior!JMHO.
Outdoor re-set will only help to provide comfort, and that can be accomplised at the boiler level...so that's where I would put it.(zoning re-set will deprive you of any savings if the boiler is always looking for 180°) Go for it. Chris0 -
Yep!
The piping diagram is getting better but, the previous thread has some good points. A primary loop should go from hottest loop set o tees to coolest. The mixxing device loops could work as drawn but will be mixxing cool water from the return of the same loop in the primary loop just before the tee that draws hot water for the mixxing valve. This will diminish capacity a tad. It would porably be less confusing to draw the hot water from the tee ahead of the return tee. I would also redesign the panel rads into a reverse return configuration or a monoflo diverter set up. Dont get frustrated you're getting there. WW
To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"0 -
Edited schematic attached with rad return reversed
The config for primary/secondary for my loops with mixing is taken directly from page 102-080 of Taco's instruction sheets for their series 5000-2 mixing valves.
Taco calls out tee spacing when this is done, at "6 pipe diameters maximum." I am still in the dark about the mechanics of flow and temperature in these systems, but apparently the closeness of the tee spacing has something to do with isolating secondary circulation from primary.
Would you please digress some for me about the panel rad return config? With the panels all on one floor at the perimeter walls, I thought the thing we would do is to run a 3/4" PEX supply header from the circulator to the rads, with a 1/2" tee-up to each. We've a great room with three big rads eating up about three quarters of the heat, so the header should route there first, before looping around to the smaller ones in the bedroom and bath.
Re "reverse return," are you saying that the 3/4" PEX return header should have its dead end at the first rad supplied from the supply header? I can understand the logic there, if that is what you mean by reverse return.
Since these rads are all TRV-controlled, and I read somewhere that a differential pressure bypass valve should be used, piped between suppy and return in a loop such as this, where do you see one going in the schematic?
And two more things, while you are helping educate me.
Does outdoor reset for the boiler control the boiler such that as temps outside go down, the boiler modulates to a higher burn output so as to move temp up in the primary circuit, say from a low of 110 to a high of 180?
And as regards my supplier's guy telling me I need a tstat on my main floor for control of the rad circuit, even though each has a TRV, is this the tstat that is set way up at middle to upper 70s, to function as a high-temp shutoff for the rad loop?0 -
Hi all!
Well the pictures are getting better but still not correct!
First off, I hope you are getting a professional HVAC mechanic to install this heating system in the home you are building. You did say you are a builder correct?
You stated in your first thread that you will be using a mod/con boiler! Therefore all the schematics above do not take full advantage of this type of boiler. The piping schematics you have posted are great for a conventional boiler because you are protecting your return water temperature to that plant. Maybe you should do a little more research on the mod/con boiler you would like to use and then you can come up with a better schematic.
Second, if you are using a mod/con boiler why in the world would you design rad. panals to be @ 180 degrees @ design? Once you start producing higher temp. water you start returning higher temp. water. Therefore your efficiency goes down the drain!
Meaning, you spent a ton of money on an 80 + % boiler???
Just my 2 cents!!!!
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Sorry! Double post....
To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"0 -
You're right DC
The circ should be located on the higher temp side of the flow.
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> Hi all!
>
> Well the pictures are getting better
> but still not correct!
>
> First off, I hope you
> are getting a professional HVAC mechanic to
> install this heating system in the home you are
> building. You did say you are a builder
> correct?
>
> You stated in your first thread that
> you will be using a mod/con boiler! Therefore all
> the schematics above do not take full advantage
> of this type of boiler. The piping schematics you
> have posted are great for a conventional boiler
> because you are protecting your return water
> temperature to that plant. Maybe you should do a
> little more research on the mod/con boiler you
> would like to use and then you can come up with a
> better schematic.
>
> Second, if you are using a
> mod/con boiler why in the world would you design
> rad. panals to be @ 180 degrees @ design? Once
> you start producing higher temp. water you start
> returning higher temp. water. Therefore your
> efficiency goes down the drain!
>
> Meaning, you
> spent a ton of money on an 80 + %
> boiler???
>
> Just my 2 cents!!!!
>
> _A
> HREF="http://www.heatinghelp.com/getListed.cfm?id=
> 289&Step=30"_To Learn More About This
> Professional, Click Here to Visit Their Ad in
> "Find A Professional"_/A_
0 -
> Hi all!
>
> Well the pictures are getting better
> but still not correct!
>
> First off, I hope you
> are getting a professional HVAC mechanic to
> install this heating system in the home you are
> building. You did say you are a builder
> correct?
>
> You stated in your first thread that
> you will be using a mod/con boiler! Therefore all
> the schematics above do not take full advantage
> of this type of boiler. The piping schematics you
> have posted are great for a conventional boiler
> because you are protecting your return water
> temperature to that plant. Maybe you should do a
> little more research on the mod/con boiler you
> would like to use and then you can come up with a
> better schematic.
>
> Second, if you are using a
> mod/con boiler why in the world would you design
> rad. panals to be @ 180 degrees @ design? Once
> you start producing higher temp. water you start
> returning higher temp. water. Therefore your
> efficiency goes down the drain!
>
> Meaning, you
> spent a ton of money on an 80 + %
> boiler???
>
> Just my 2 cents!!!!
>
> _A
> HREF="http://www.heatinghelp.com/getListed.cfm?id=
> 289&Step=30"_To Learn More About This
> Professional, Click Here to Visit Their Ad in
> "Find A Professional"_/A_
0 -
> Hi all!
>
> Well the pictures are getting better
> but still not correct!
>
> First off, I hope you
> are getting a professional HVAC mechanic to
> install this heating system in the home you are
> building. You did say you are a builder
> correct?
>
> You stated in your first thread that
> you will be using a mod/con boiler! Therefore all
> the schematics above do not take full advantage
> of this type of boiler. The piping schematics you
> have posted are great for a conventional boiler
> because you are protecting your return water
> temperature to that plant. Maybe you should do a
> little more research on the mod/con boiler you
> would like to use and then you can come up with a
> better schematic.
>
> Second, if you are using a
> mod/con boiler why in the world would you design
> rad. panals to be @ 180 degrees @ design? Once
> you start producing higher temp. water you start
> returning higher temp. water. Therefore your
> efficiency goes down the drain!
>
> Meaning, you
> spent a ton of money on an 80 + %
> boiler???
>
> Just my 2 cents!!!!
>
> _A
> HREF="http://www.heatinghelp.com/getListed.cfm?id=
> 289&Step=30"_To Learn More About This
> Professional, Click Here to Visit Their Ad in
> "Find A Professional"_/A_
0 -
> Hi all!
>
> Well the pictures are getting better
> but still not correct!
>
> First off, I hope you
> are getting a professional HVAC mechanic to
> install this heating system in the home you are
> building. You did say you are a builder
> correct?
>
> You stated in your first thread that
> you will be using a mod/con boiler! Therefore all
> the schematics above do not take full advantage
> of this type of boiler. The piping schematics you
> have posted are great for a conventional boiler
> because you are protecting your return water
> temperature to that plant. Maybe you should do a
> little more research on the mod/con boiler you
> would like to use and then you can come up with a
> better schematic.
>
> Second, if you are using a
> mod/con boiler why in the world would you design
> rad. panals to be @ 180 degrees @ design? Once
> you start producing higher temp. water you start
> returning higher temp. water. Therefore your
> efficiency goes down the drain!
>
> Meaning, you
> spent a ton of money on an 80 + %
> boiler???
>
> Just my 2 cents!!!!
>
> _A
> HREF="http://www.heatinghelp.com/getListed.cfm?id=
> 289&Step=30"_To Learn More About This
> Professional, Click Here to Visit Their Ad in
> "Find A Professional"_/A_
0 -
Are you aware, Jamie . . .
That there are actually places in these here United States where getting a professional to do this is impossible? And that my location is one of those places?
Please suggest to us a nice really cheap boiler to use, instead of the $2000 Munchkin T80 we were going to go with.0 -
Where?
Gene, what part of the country are you in?0 -
The project is located near the small town of Ausable Forks, NY. Most things built there are done by "jack of all trades" folks who do their own everything . . . plumbing, electrical, heating.
The permitting process is laughable, there are no licensing requirements, and the furnace servicing is handled almost entirely by the fuel suppliers. More people heat with wood and kerosene monitors than with anything else.
Essex county is one of the poorest and least populated counties in the state, and the second largest in area. There are few roads, and no local police at the town or county levels. State troopers are all we've got.0 -
Gene
Jamie brought up some good points. There are a lot more ways to screw up an installation like this than to get it even close to right. DO your homework.
Condensing boilers shine (efficiency wise) with low return water temperatures. With 180* design temperatures for the panel radiators the return temps will be high slashing the efficiency. You might consider a more initially cost effective cast iron boiler. Most operate at 84% AFUE. Check the boiler manufacturers websites. Most have pretty explicit piping diagrams.
Outdoor reset will lower the circulating temperature as the outside temperature rises from design (180*@??OD temp)
This is a huge energy saver regardless of boiler choice.
As to the thermostat question....it depends. If all you had was panel radiators, TRV's, AND outdoor reset, you could maintain indoor temp by constant circulation and the outdoor reset curve. Adding the radiant floor zones makes things a little murky. I think you should use a three zone pump panel with three thermostats, add TRV's on some panel radiators you might want to throttle down (little used rooms?) and run with it.
Even though you might not be able to get a qualified installer up your way you should still get a professional to design.
Best of luck0 -
Thanks for the kind response
I have become convinced, though your advice and that of others, to consider a boiler such as the W-Mc CGi. I looks as if my general schematic for the various loops is viable, and now I am focusing on controls.
Tekmar's site has some great resources, and I have been eagerly reading the various "essay" docs there on loop schemes and controls for them.
Could you expand a little and describe what is meant by a 3-zone pump panel? I'm envisioning a tstat for the hot loop (the one with the 6 panel rads) and one tstat each for the two radiant zones.
Furthermore, how would outdoor reset play in all of this?
I am going to get a professional to design it, but I know how widely opinions can vary among professionals, and thus I want to know all I can.
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This is how
> I have become convinced, though your advice and
> that of others, to consider a boiler such as the
> W-Mc CGi. I looks as if my general schematic for
> the various loops is viable, and now I am
> focusing on controls.
>
> Tekmar's site has some
> great resources, and I have been eagerly reading
> the various "essay" docs there on loop schemes
> and controls for them.
>
> Could you expand a
> little and describe what is meant by a 3-zone
> pump panel? I'm envisioning a tstat for the hot
> loop (the one with the 6 panel rads) and one
> tstat each for the two radiant
> zones.
>
> Furthermore, how would outdoor reset
> play in all of this?
>
> I am going to get a
> professional to design it, but I know how widely
> opinions can vary among professionals, and thus I
> want to know all I can.
0 -
This is how
I would do it.0 -
Wow! Jed, thanks, but explain for me
What I am seeing is that your "hot" loop, the one with the panel rads, is identical to mine. Supply and return from a primary loop with closely spaced tees, reversed returns, and a diff p bypass valve at the end.
I don't know the reason for it (please explain) but you have a primary loop separated by a boiler loop. I see a circulator in the boiler and a circulator in the primary loop. Is this necessary for boiler protection?
Your two infloor radiant loops look identical in the config of the schematics to what I had drawn, but you call out the I-series Taco mixing valves with outdoor reset. That is what I think I am seeing . . . the resolution isn't the best with my system and monitor.
May I presume that each of these I-series valves would be set up with its own heating curve (one appropriate to its own zone's floor covering) and use the same outdoor sensor?
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Yes, Gene
Sorry for bad resolution. I don't attach many dwgs, a little clumsy. The boiler I have there is a Biasi Riva. It is a modulating gas boiler, but not condensing. Since you have 2, possibly three water temps, the Riva will operate your high temp rads, and you can benefit from the i-series valves nicely. Simple control logic, good system efficiency ( the Riva is not a condensing, high efficiency boiler). It comes with a Wilo circ, flow switch, small exp tank ( you'll need a system exp tank).
The dwg was done quickly, you may not need the Primary loop as I have drawn. Use the Wilo as the Primary circ. But it must be 3/4" Primary loop, due to the Wilo and the flow switch. The Wilo is capable of up to 6.2 gpm @ 1.75' hd. This isn't the only way. But this boiler would seem to fit your needs efficiently and economically.
Each Taco i-series valve would use it's own OD sensor, but can be mounted in the same enclosure.
Jed0 -
why not?
tie the floor radiant to the bottom is the floor radiant? all in series?
if you are using constant circ, the floor will always require less than the panels rads.
this would give you the lowest possible return temps to the mod/con.
you could biuld in a bypass if the floor required higher temp than the panel rads were retruning.0
This discussion has been closed.
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