Crazy zoning idea?

Lordniacin

OK, I'm the guy with the crazy converted gravity/hydronic system with like 150 gallons of water in it for the first floor alone....

I'm looking ahead to eventually adding the two upstairs apartments as additional zones.... Zone valves, or circulators.... Thing is, I really like the idea of continuous circulation in each zone. First for comfort, but also to avoid accumulating random 20-gallon slugs of cold water here and there to crash down into the hot boiler whenever the zone turns back on.

So my idea is to take each zone's supply and return and bridge them with a circulator, and also a closely-spaced tee.
Meanwhile my boiler would have a manifold on the output side with three zone valves. When a zone calls for heat, the zone valve opens and the boiler fires, injecting hot water into that circulating zone loop.
Each zone has a higher circulating flow than the amount of new hot water trickling in (especially when all zones are open at once!). This helps disperse and circulate the hot water around the zillion gallons of radiator water in each loop for more even heating. When the zone stops calling for heat, the hot water continues to circulate within that zone, evenly cooling off.

I'd like to ask the experts: is this idea obvious, crazy, somewhere in between?
My main concern is that flow through the boiler would change somewhat depending on whether one, two, or three zone valves are open. But it is not like the zone valve is leading to an actual whole zone, it is leading to a closely-spaced tee, which should have near-zero head loss across it, right?
I mean, from the point of view of the boiler circulator, first it is pushing water through a boiler with a few feet of head loss, then on the other side are either one, two, or three connections with near-zero head loss. Seems it should hardly matter to the backpressure and flow how many are open. But I could be totally wrong about this.

Attached is a rough sketch if that is helpful. Looking forward to having the experts beat up the idea!

Gordy

My first question knowing little about your system, and the heat losses of each zone. why are you pumping such high gpm through your zones with an 80k boiler? If your total load is 80 k with a 20 delta then 8 gpm should be enough flow. Why would each zone need to be so much higher when a single zone would be less than the

Lordniacin

Sorry, I put this info in earlier posts. I will amend the drawing. The losses of the zones on design day are like 35K, 20K, 15K.

The point of each zone having "higher that you might expect" flow is that it is a converted gravity/hydronic system with a vast amount of water in each zone in radiators and ancient huge feeder pipes. Just to get the water to go around once every 10 to 15 minutes per zone would be a great goal to increase comfort. Right now it is far less than that.
Ever since the genius gas conversion of the previous owner in the 1970s, it works like this: each apartment calls for heat, the flow is only the scant few GPM that suits the apartment boiler, and that slowly works its way into the zillion gallons of the radiator system. The closest radiator gets hot, maybe another, and then the overall heat demand is satisfied. Insulation upgrades have left every apartment vastly over-radiated, so heat demand is reached long before the furthest radiator is hot.

To increase comfort, I'm asking feedback about this scheme. Each zone will have its vast bulk of water spun around by its own constant circulator. From time to time, the boiler will inject new hot water into one or more zones via zone valves. Does this make sense?

Gordy

I'm a little confused. In the other thread you ripped out the 3 boilers 100k burnham boilers, and installed a TT mod/con correct? So why not pipe it direct, and why the mixing valve? Mod/cons love the cold return water. Anything under 130* is making the boiler more efficient. You are using outdoor reset function correct?

Also I see trvs on rads, and your using zone valves.

Gordy

Think carefully the high water content of the gravity system is also acting like a buffer tank. Mass is your friend with condensing boilers.

Unless this is a concept drawing for a CI boiler in a gravity system.

Lordniacin

Actually there are still two ancient AO Smith boilers still in the system, I'm just thinking ahead. I suppose this diagram could work with either condensing or non-condensing.
The thing with condensing is that you need the input somewhat below the condensing temperature, but the output somewhat above the condensing temp! Seems even a condensing boiler can benefit from some kind of input water tempering scheme (HX, 4-way mixing valve, etc.) if you are going to start it out trying to eat 200 gallons of water at 60 degrees. Poor thing is trying to put a 100 degree delta on all that water. And suppose for all its clever internal throttling and bypass it can only manage an 80 degree delta. The output water would only be at 140, maybe the non-condensing coil would be forced into the condensing range too! Bad.
I'm realizing that 200 gallons of very cold water is a challenge to anything, without some kind of input tempering scheme....

Gordy

If your running ODR there should be no cold slugs of water with constant circulation. You water temps should be just enough to off set the load.

Lordniacin

Gordy, what I have on hand to install is a non-modulating, non-condensing boiler. But I sort of have ODR anyway because of the huge water mass. Put it this way: in September my radiators may be at 85 degrees, in October at 95, in November at 115, in December at 135. That's just how it naturally works. The temp rises until it just balances the heat load, then the boiler shuts off and "coasts" for a greater or lesser time. The huge water volume averages it all out. It is really quite even and comfortable.

When I bought this place all three boilers were rigged for constant circulation. That's just how it was done. You had a lot of water looping around and from time to time you put some fire under the part of the loop called "boiler." A little tweaking of the heat anticipator setting on the old Honeywell round thermostat and you had an amazingly stable temperature.

I guess that is what I am trying to replicate here with my crazy diagram. Three high-volume constantly circulating loops. But instead of three boilers, one boiler that instead uses zone valves and tees to inject hot water into one or more of the loops as needed.

I was just curious because I have looked at a LOT of heating system diagrams and never quite seen this exact setup before. So I was curious if someone would say: "That is nuts!"

hot_rod

Very similar to the mini tube injection systems. In your case you are not looking to blend down temperature, correct?

If so those manifolds will need to be sized to handle the flow when all 3 zones call.

If you plan on running the zone circs constantly, look into a ECM, even in fixed sped mode you will get a good reduction in pumping costs.

Gordy

Most well designed heating systems mimic indoor reset. Simply put the boiler runs long enough to satisfy the thermostat. The awt ends up being what ever it is. The shorter the call the lower the AWT. The longer the call the higher the AWT. This obviously correlates to warmer, and colder outdoor conditions. No magic just a well located thermostat. All though with Ci boilers return temps need be addressed.

So in your gravity system project did you remove the gravity piping?

Maybe your bouncing back and forth with your diagram, and there is no correlation as to your project.


Your diagram is basically a parallel primary loop design. The zone valves are a redundant feature.

May I also,suggest downloading caleffi idronics series. Very informative,.

Lordniacin

Thanks for the tip!
Not sure if I'm completely understanding the question, but I'm not planning on blending any temperatures down.
On the return to the boiler I was planning on an ESBE valve to blend temperatures up to insure minimum 140 return. Whole months can go by where my vastly over-radiated system never has to exceed 100 degrees to satisfy demand.
OK so say the return water is at 60, the ESBE valve boosts it to 140, it leaves the boiler at 160 (but at very low flow rate because most of it is going back round the bypass loop), and then the trickle of 160 water finally coming out is injected into one or more loops to gradually bring the radiator temperature up to 100. (whew, brain already tired!)

I was planning on 1.5" manifolds to feed the three zone valves, each one coming off a 1" port. So the manifold itself is like a little low-loss header, and the nearest valve opening won't rob the flow from the furthest valve... I think.

Thanks for the tip on more efficient circulators. I was thinking about some kind of... not sure what you call it... summertime reset? Like if the outdoor temperature goes above 60 degrees or so, the whole system shuts off to save electricity.

Thanks for bearing with me, I am still very new to this, still trying to wrap my mind round the concepts.

Lordniacin

Hi Gordy, no, I did not remove the gravity piping. There is still vast amounts of water in the system. Yes, I am still going back and forth on different topologies, wondering which is best. I have read the Idronics series--very informative!

OK, so it is a parallel primary loop design. Didn't catch the name for that before. But each loop is to a different apartment. I wanted to preserve some autonomy for each apartment to set it's own temperature. Hence the zone valves that inject heat into each particular loop only when that apartment is calling. Maybe I need to re-think it again, and I thank you for that. I want to work it out on paper before working it out in copper, and perhaps making some goofy mistake in the basic concept.

SWEI

Repipe it primary/secondary using a 3-way or 4-way Taco iSeries-R valve and use two pumps -- one for the boiler and one for the system.

Gordy

I did not want to give an opinion until we had most of the information on what you are trying to achieve. Sort of crossing over from other thread you started. But yes pipe it like @SWEI recommended. I would keep the gravity pipes unless it's hindering some grand renovation. Save dollars in new piping, and built in mass is your freind. I think you view it as an enemy. You just have to master control tactics.

Lordniacin

I guess I'm not quite picturing how two pumps and a mixing valve gets me constant circulation in each of three zones (one to each apartment) along with independent temperature control of each zone. Could you explain a little more how that would work?

Or do you mean more like three mixing valves, one per zone?

SWEI

• One pump for the boiler.
  
• One pump for the system.
  
• One reset curve.
  
• Three proportional zone valves (one per apartment). TRVs with remote bulbs would be the least expensive commonly available way to implement this. An electronic implementation would currently require DDC, though I don't yet have a way to remotely support this size system at a competitive price.

NYplumber

Can the system be configured with TRVs at each radiator? In that event you can run any boiler with or without ODR and just have the radiators that need heat on. I think your over thinking things with your drawing from the first post.

Lordniacin

Really sorry if I was unclear. Three zones. Each zone leads to an apartment. Each apartment has a thermostat. If apartment #3 takes a vacation, they can set back their space to 55 degrees. If apartment #2 like a deep nighttime setback (and they do!) because it "helps them sleep better" they can set one.

I appreciate TRV's but no apartment here is so vast that it needs room-by-room control. All rooms in a given apartment are in daily use. I appreciate ODR but essentially I have it anyway. In spring and fall the radiators will get up to 90. In January they might get up to 150. A natural consequence of the over-radiation and high water mass.

So what I'm really looking at is an upgrade, working with what I already have and preserving the parts that works well. Which is most of it. I'd like to preserve the constant circulation per apartment that makes the heat so even. But, replace three dodgy old boilers with one better boiler that is rightsized to the actual total building loss. One boiler; three cheap zone valves that inject hot water into already existing constantly-circulating loops as needed to meet demand. That is the gist of the idea.

Gordy

Okay so you don't have ODR. While your system may seem to mimic such. It's quite different. ODR is more predictive. Instead of waiting for the structure to already cool as with thermostat sensing. The outdoor sensor is already picking up the temperature trend, and making water temp adjustments.

Since you have a ci boiler you need to protect it from sub 135 return water. Once you switch to a mod/con in the future that sub 130 return water is your freind.

Constant circulation can be done with two pumps instead of the four you have in your drawing. The proportional zoning comes in play when one of the tennants chooses to set back, or have different day time temps than another apartment. It merely closes flow down to suit the desired temp setting. Maybe at 55* the proportional valve is just a trickle of flow. While the guy who likes it 72 is at wide open full flow.

The advantage of course is two pumps running constantly instead of 3.

So primary secondary at the boiler using ODR. The secondary is constantly circulating with a delta p, or delta t pump. The proportional valves,are opening and closing proportionally (not full open, or fully closed) to the apartments as btus are needed.

Paul48

Gordy....He says the 3 constant circ loops already exist. He doesn't seemed as concerned about efficiency as he is comfort. He's just removing 3 boilers and manifolding 1. The ESBE, will protect the boiler. He wants the constant circulation. All other misconceptions aside, his plan will work, for what he wants.

Gordy

Agreed Paul it will work.

Gordy

No one said you need a Belimo CCV. Kurt said a remote trv would be least expensive.

At any rate a pump, and a zone valve is what 300 bucks x 3. In comparison to one pump, and 3 remote trvs?

Paul48

How about P/S instead of manifold, with 3-way zone valves on the secondary side? It gets you away from series circs.

Paul48

And with P/S and a DT circ, isn't there a way to provide boiler protection, on a fixed firing rate boiler, with just the circ? I think that's the most commas I've ever used in a sentence.

Gordy

IF the OP is gutting the gravity piping the high mass goes away, or at least some of it no?

The drawing is conceptual I believe with no vision of what is there, or how it is presently piped.

If there is future HE planned then the piping, and control should be set up in a configuration to make the change over with the least amount of work as possible, and loss of unusable hardware.

JMHO first cup of Joe

SWEI

Proportional flow control really is the key to making a high mass system behave. Remember that water, iron, brick, concrete, and rock all constitute mass.

Small CCV's cost roughly $10 more than a decent zone valve. It's the controls that are lacking. I'm working on that...

Harvey Ramer

The piping drawing that is posted is conceptually sound but realistically flawed.

The ESBE valve will not likely provide proper function with the ever changing pressure loading on the system side. And if it does marginally work you will very likely get velocity noise that will transmit through the entire system, while only one zone valve is open.

A good way to pipe it would be to replace the zone valves with 2-way Taco I-series valves to serve as actual injection mixing with ODR, zoning and boiler protection. Do away with the ESBE valve. Pipe the boiler loop to the supply manifold - Pressure bypass valves - return manifold - boiler.

This will give you the complete package with everything you are looking for and a bit more.

SWEI

Clever, Harvey. A tad pricey, but clever.

We recently put together our first two "system" packages with proportional zone valve control. Three zones (including room stats) plus two boiler calls runs about $1,000. If I had a way to remotely support/provision them and a UL 508 shop, we'd be off and running.

Paul48

I don't think he has intentions of gutting. He says the 3 constant circulation loops already exist. The OP has only ever mentioned comfort, not efficiency. He's happy with the sows ear, he doesn't want the silk purse.

Lordniacin

Wow, thanks for all the feedback!

Really, I am just trying to solve two problems here.
-- I need about 15 GPM in my huge basement feeder pipes to break the thermosiphoning effect and get the heat all the way to the far end. (I have experimented with a three-speed circulator to find out). Yet that is not well-suited to an 80K boiler that wants more like 8 GPM to get a 20 degree delta. So I need to decouple those two flow rates with some sort of P/S setup.

--I need to deal with 150 gallons of system water that in the shoulder season might start at 70 degrees and only get up to 90 by the time the call for heat is satisfied. In short it is almost always too cold for a cast-iron boiler. This points to some kind of input water tempering like an ESBE valve.

--While doing these comparatively small changes to the near-boiler piping why not set it up so I could, in the future, add the other two smaller apartments to the system? Leaving their constant circulators in place, simply removing the old clunky boilers and figuring a way to inject some hot water into 'em as needed?

Sure, if I were starting all over again with a big pile of cash it would have P/S, ODR, TRV, and all the other acronyms. Probably controllable by cellphone from Paris. But I'm just a guy with an old house looking at solving the issues of even heating and excessive cold water return.

I SO MUCH appreciate all the ideas you have thrown at me! This is such an incredible forum.