are there really 10-1 mod cons

hot_rod

I simply can not conceive how a modcon can not hand a variable speed pump in the current year, so yeah when Harvey said "appropriately zoned" i gave him some cheerful guff I apologize to him and the crew who have been so patient with mt if it didn't come off as jocularly as i intended it.

It is exactly as you mentioned with air side equipment, VS and frequency drives have been around in the pumping industry, including hydronics for decades.

Just like the air side it took time for it to filter down to residential equipment affordable prices, we are just starting that voyage here in the US.

The DOE recently required all pumps over 1 hp will be electronic, ECM technology to meet energy standards. I suspect fractional HP pump motors will follow within a year or two. As that happened you will no doubt see more of the European technology for small residential stuff become available and prices dropping.

The second obstacle is getting the control logic of the circulator and boiler operating logic on the same page, that is about where we are stuck now. sounds like matching a dragster and a semi, they have different mindsets.

I don't know of any company, yet, that manufacturers the boilers and the pumps, so we come at the solution from two different directions. Also keep in mind every boiler has it's own control and proprietary logic, so the smart pump needs to communicate with all the dozens of boiler controls out there, easier said that done. if it were simple, we would already be there.

The solar controls that we sell allow you to select Grundfos, Wilo, or Laing setting for the PWM choices, so even the pump manufacturers have different control algorithms.

I also agree gathering data is critical to understanding and improving system operation. That can be done electronically or by a human being sitting on a bucket. Without gathering and analyzing data, really you are just guessing or following and trusting marketing hype.

keyote

Rich
I know zones are not determined by Sq they are determined by do you control them separately and before you decide that you see what their demand is , My point is that on a 60 degree day it takes 2500 sf of this home to require 1-1,4 gpm and 6-7 kbtu which makes it as small a zone as i can do with a 10-1 without multiple pumps burning more in pump electricity than im puttin in the floor.And i just think expecting people to settle for that as a zone rather than fixing the two problems using ecm pumps without P/S is crazy while meanwhile the ten million things these boilers can do, like decide if your pump needs to cycle for 20 seconds because its been dormant for 24 hours.

keyote

LOCHINVAR SAYS

so i just got off the phone with lochinvar first two useless tech support then their rep whos attitude "was play it safe pipe P/S **** the homeowner" I finally spoke with a marketing guy david george who i was told is an engineers and hes says this new KHN is specifically designed to use variable speed pumps and they like taco pumps and communicate fine with variable speed pumps that they stand by their no P/S configuration even with a variable speed pump. That as long as your small zone is equal to lowest modulation you are good to go but that yes its true there are half a dozen other ways to redundantly assure this. first their are safety low water and low flow that dont simply just off though they will if need be the pump control does indeed set minimum pump voltage to determine strt speed, that also co ordinates with combustion rate. the boiler never starts in more than 255 and can be set all the way down. They do solve this on there other boilers by requiring a differential bypass and no reason this could be done here.He also note that this KHN boiler is a fire tube and has more mass and more forgiving than less recent versions
also as i said it seemed to me like the variable speed pumps dont actually pump less than 1-2 gpm with even boiler head and the VT is able to be programed to raise its curve specifically to adress minimum flow.
However as knowledgeable as this guy was there another guy Dan reddick who is supposed to know more but was out. who i will talk to because there is a line in the manual that says certain variable speed pump setting to be used with P/S.
I also am not at all taking lightly the cautions of you guys i have been a pest specifically because i am convinced you know what youre talking about. I am hoping lochinvar has fixed some things with this boiler that needed it.
One thing that would make me be ok with being the guinea pig is if i could use this differential bypass idea, if thats even what im envisioning would be called.The other way i explain it is to think of the boiler having a zone valve that open with any valve and ensure minimum flow without another pump, if that is not ignorant and would protect the new boiler id be willing to risk having to repipe if anyone wants to explain how it might work

I have another crazy idea if anyones still listening. what if the indirect was the primary, i know it its going to be hotter water so youde need to put in a tempering valve on your "secondary CH loop " and it might be tricky getting the temperature setting on the indirect to work for both purposes but off the top off my tin head id say it would be doable. But at least if youre having to fire up a second pump youre firing a pump you have to anyway.

HEY WAIT WHAT IF YOU DIDNT EVEN HAVE A SECONDARY WHAT IF YOU PUT A ECM ON THE INDIRECT AND JUST CAME OFF IT WITH A TEMPERING VALVE TO ZONE VALVES SO........ GOT ya lol

Rich_49

You will probably see (will see) that if you change the outdoor temp on your design program that the head and flow along with temp of all your circuits will change , you'll also notice that the Delta will remain unchanged . That is why it is called a designed for Delta . Hatteras is mistaken that the VT2218 loses it's benefit when used on the secondary side exclusively . It will maintain your designed for Delta for more of the season than any other circ . There will be disagreement on this point , . As zones open and close the VT2218 will respond almost simultaneously as Hatteras can attest to . If you do not guarantee a minimum head through a circuit you will get below the low end and the pump curve and the circ will have it's way with your fluid . Example ; If you need to insure 1.5 gpm through your secondary or system side piping you must guarantee2.5 feet head .

Don't get lost , you are attempting to build a system and once again someone is only looking at one side of the equation or hydraulic separator as it were . You cannot do this and expect acceptable or even good results .

If one uses a 10 or 15* Delta T on the system side and the boiler is set up for a 20* Delta as many boilers are you will in fact be in great shape . If boiler is flowing 1 gpm and system is flowing 1.5 or 2 gpm all heat will be moved to the system side and the boiler should operate as designed and tested
Finding the way to guarantee that for the largest percentage of a heating season is the key . All design efforts cannot be only in the mechanical room , they must be done throughout every aspect of a system . Direct pumping a 10:1 can be done successfully in the right type of system when all the numbers work , you just have to know what numbers to look for and if they are not conducive you must use P/S piping , it's that simple .

keyote

Ahh hatter there you are. Let me catch you up. you sort of came into my drama in the middle i started out a month ago wanting to swap out the TT110 3 speed for a ecm and pump through i too have i think a low mass [radiant under hardwood 52kbtu] project and the idea of having to run two pumps for a small zone call drove me nuts it was the antithesis of the whole radiant heat mod con ecm spray foam triple pane point of my build.
BUT TT110 5.5 turned out to be 30k not 20 k my heat load turned out lower than anticipated and i didnt understand the minimum flow requirements and a lot of other things, since i had found a dirt cheap TT110 used and was still under renovation and not seen the new build actually operate i tried to make the TT work with a buffer but it got complicated and expensive enough i realized i really ought to reconsider getting a new boiler sooner than later,

you came in during the buffer part but some were still refering to my wanting to pump through and i was thinking at least with a buffer the energy is used later.Im not even quite sure how your story got into my thread because by then the buffer made it P/S but then yesterday when i became serious about a 10-1 modcom, HTP or KHN the whole ecm pumping thing seemed to me to be back into play, except i remembered your comments and then hotrod seemed to confirm there was a problem with electrical or software between pump and boiler controls, and gordy seemed to see it more as a flow fire pump cycling problem. and rich says its not a problem at all.
so here we are any detail you can shed i would like to hear no one has favored the HTP or lochinvar though I think Im liking the loch probably because its manual seems to be a bit more explicit about this topic. supply house has the unit pretty reasonable.
If you have read this thread carefully i quote a lot from the manual and talks i have had with loch today i wouldn't say it is conclusive but it seems a bit hopeful. I can tell you the loch not only uses return water temp it uses system water temp and it uses heat exchanger exit water temp and tries to keep a 2 degree differential
between Hx and system, and it uses a delta t just across the heat exchanger and it coordinates those reading they say to both pump controller and fire controller, they are adamant that it has no problem communicating with variable speed pumps and say they have not heard of any problem with the ecms and kHNs but could not say about vt2218 specifically. I mentioned several other safety features, but all that said, it does still have a 1gpm minimum flow at low fire and i have manifolds that under say a 60 degree day may require only 1 gpm, to say nothing of loops i would like to zone individually.I dont know if you have that situation. And while the manual is clear about pumping through and variable speeds its a tiny bit less clear about combining them, though the guy i talked with said its only because of minimum flow and if you keep zones above the lowest mod youre good. I frankly don't understand enough to know why the boiler cant simply be fed some extra water for safety when a zone opens.

Rich_49

Narrowing Deltas on the system side directly relate to RWT s Hatteras .

I stand corrected due to a mistake trying to help someone . I drew vertical at 2.5 gpm as opposed to 1.5 . Just like I tried to assist you in saying that to not pump below 1 gpm you would need to insure about 3.6 ft , you did not .

Graphs don't confuse me , especially pump curves . Have you figured out yet that in Delta T operation the whole shaded area is in play as opposed to riding up one of the four curves ?

Gordy

I hate it when mom, and dad fight

keyote

Thank you rich
yes i changed the "design day 17 degrees to 60 degrees to see how low the lowest riser/manifold load on the warmest day might be and figure out if it was within the lowest modulation of 8500 btu and flow of 1 gpm. My lowest demand manifold is .98 gpm and the highest is 1.45 gpm the lowest head is 3.2' my DT is locked at DT 15 so Im close. But all of the manifolds are too low on btu demand im hoping that just means the call will end sooner.
I calculated that because i would like to avoid secondary. i do know the KHN can be set for DT down to 15 at least and since on gordys advice i went from a design of DT10 to DT 15 to get total flow and head within curve of a variable pump that is low enough.
my real 17 degree design day total load at DT15 is 7.2 gpm and 6.7 head plus 2.0 head for the boiler
so thats my system low mass radiant and an indirect

Now im really hazy at seeing the numbers move at the same time and as ive said many times i am not sure how the system is supposed to be controlled. But the way i can imagine it works is

I use the VT2218 to maintain the DT15 i used in loopcad
I use the boiler to maintain the water temp
I use a outdoor reset to adjust that water temp for outside temp still holding DT15 on pump

I sort of get that the flows and heads will not remain constant as that happens, [just like lowering the DT to 15 on gordys advice dropped my head flow into curve]
But Im hoping i dont have to worry too much about that because....

I know my total heads flows on design day and now i know them on 60 degree day on just the lowest demand manifold so if those flows/btu are within the boilers minimum or i can find a trick to make it work im good.

Im also vaguely aware theres another approach to control, to keep water temp stable and increase flow instead this seems harder to imagine and liable to mess with my hard won conformity to pump curve,

so as far as i can tell i have a simple system reasonable flow head dt etc and if i can meet the minimum flow requirements which im really close to i should be able to avoid P/S do you agree?

as to meeting that 1 gpm i have asked about several approaches.
One is do these pumps even pump less than 1 gpm and the vt2218 says you can raise it curve to get it to pump a minimum since my worst case is really close would it really hurt to nudge it up i would tink all that happens is call is met sooner.

The other idea is this bypass loop for the boiler I didnt understand what you were saying about that

keyote

Hatteras good point within the variable curve a 1gpm flow does seem to require 3 1/2 feet now i know you can adjust the band up i can't recall if it could be lowered as well my manifolds are close but within range i can still tweak the loops to get them a bit higher without losing it on design day

keyote

Hatteras not sure if it would help your situation but today i saw on the taco site thae VT2218 variable curve is adjustable i think it was adjustable in both directions.
You are preaching to the choir about P/S being a waste these days. But let me stipulate a few years ago when i first read Halorans book a was enthralled and still am at the ingenuity of the old timers, but sadly in a way computers are making it obsolete. But since we may not be entirely there yet no one commented on my idea about using the indirect as the primary loop yeah you still have a second pump but its a pump that was really a third pump doing double duty. I even teased gordy that it could be an ecm lol

keyote

Hatteras or rich regarding the 2218 what happens below the variable curve?

hot_rod

Hatt has it right, you need to apply the mixed temperature formula when you use P/S, hydroseps, or even a buffer tank. The various flow rates and temperatures get crunched into the formula to define that RWT to the boiler.

If you are applying condensing technology, you strive to keep that RWT low as possible. Idronics 15 is a good read for that concept, cause and effect..

I'd also caution you about your expectations of fixed ∆ pumping on the distribution. The ∆T on a hydronic system is dynamic, just as the heat load on the building is ever-changing.

Some excellent, non pump bias reading on that topic in Idronics 16. Follow the examples of this with fin tube, radiant slabs and panel rads, this is the takeaway supported by the number crunching and some of Hatts bucket seat data logging

The notion that any heat emitter wants to or can remain at a fixed ∆ as flow rates change (varying the pump speed) is not supported by these results.

But we have been down this rabbit hole a number of times here, more questions than answers. Comb through the archived posts.

Harvey Ramer

So let me get this straight. You have a bunch of radiant zones and you want to direct pump a modcon boiler with no buffer?

Disclaimer;
I didn't read the whole thread. I have the attention span of a gold fish.

Here's what I would do in your situation.
(And you should be quite capable coming from an HVAC background.)

To direct pump it in your application, use a Delta-p pump that is either plugged in under constant power or powered from a pump relay that activates on a call for heat. Don't worry about deadheading it. Next, install a flow switch that meets the correct spec for the boiler's minimum flow rate. Mcdonald-Miller makes good reliable flow switches. The purpose of the flow switch is to make or break the signal for heat to the boiler. In other words, enough zone valves/actuators have to be open (pump will automatically increase flow) to trigger the flow switch and activate the boiler. That will eliminate short cycling all together.

You may say that this will defeat the purpose of zoning. It won't. Any mixture of zones can be on at any given time. If one zone does not quite satisfy by the time another does, it will simply remain open till the next zone opening creates another call.

If you want to get even more techy, here's another one for you. Most boilers publish the minimum flow rate at full fire. Many boilers on startup, ramp up to stabilize the flame and then modulate down. So you can see, a higher flow rate is desired on the initial call for heat which should then be allowed to modulate downward to meet system requirements. If you use the flow switch to establish minimum flow at full fire, in the first scenario it wouldn't allow the flow to reach the absolute minimum that the boiler can handle at low fire, before breaking the signal for heat. To get around that, use the flow switch to activate a latching relay that makes and breaks the call to the boiler. The latching relay will only drop out when the system call for heat is removed.

Sequence of operation,
Thermostats start calling for heat and opening zone valves. As more valves open, the delta-p pump increases the flow. Once the flow is great enough to meet the boiler's minimum requirement for startup, the flow switch activates the latching relay and passes on the call for heat to the boiler. The call for heat to the boiler remains intact, irrespective of the flow switch position, until all the system thermostats are satisfied, which in turn, drops out the relay.


And if the KHN has all this stuff built in already, well then gravy! I haven't studied that boiler in great detail yet.

keyote

Hot rod Im not sure if you were talking to me, i just read hydronics 15. its about air dirt purging and hydraulic separation not sure how thats germain.I mean i think i understand separation in P/s and even liked that feature of buffers but im trying to avoid two pumps and P.S altogether with this KHN 10-1 modcom im considering. Lovhivar assures me this new model wont have trouble with a variable pump as you were concerned, and if i can only match my lowest load to its lowest 8500 modulation and 1 gpm flow im good. my problem is im really close but would like to have some safety like a bypass.

The hydronic 16 you pasted is about selecting DT yes i selected DT10 at first on my radiant design, but it put my design day flow head too high for the variable pumps so a tweaked the layout and fixed the DT15 and dropped well into the variable curves.
I think you are trying to tell me I am thinking about how to control wrong that i cant hold use pump to maintain dt and boiler control water temp. I will read and see if it helps it was siggys book that explained you either change the flow or the temp and i liked the dt pump because its curve works better on my system

keyote

Aha Hotrod i may see what youre saying ,went back into loop cad and realized the "DT lock" doesnt do quite what i thought, I was under the impression that i was fixing my DT and that pump would keep it there and i would adjust btu by raising swt made sense to me but i see that would be difficult without zoning every loop which i thought i was going to do but cant
heres what it says

Design versus Actual
Setting the design temperature drop to a specific value, say 20 °F, does not always mean that every circuit can be designed for a temperature drop of 20 °F. In fact, it may often be the case that only one circuit will have this value of 20 °F, and the temperature drop for all other circuits will be higher that 20 °F. The setting for fixed or variable temperature drops affects how the program deals with this issue.



The fixed or variable temperature drop setting is available on the New Project Wizard (applies to entire project) and at the Radiant Settings step of the Project Settings step as shown above (applies to each of the major construction types). The choice you make for this option will be dependant upon your overall design philosophy and objectives.

Fixed Temperature Drops
If fixed temperature drops are specified, then all circuits within the scope of the setting will be assigned the Design Temperature Drop value regardless. The flowrates will then be calculated using this design temperature drop, but they will not be throttled, or lowered, to compensate for any overheating issues.



If the load requirements vary greatly for rooms within the same zone, and the circuits are connected to the same manifold, then you may see two temperature drop values displayed as in the example below. The first value, 20 °F in this case, is the design temperature drop. The second value, 24 °F, is the maximum temperature drop that can occur at the specified water supply temperature and at the design outdoor conditions (i.e. coldest days).







There may also be control problems that you will need to address. Due to the fact that a single water temperature must be delivered to a manifold, all circuits connected to that manifold will be supplied the same water temperature. The actual water temperature delivered is normally the maximum value for all of the connected circuits.



For example if Circuit "A" serves Room "A" and has a unit load of 20 Btu/hr/ft2, it may require a 110 °F supply temperature, and if Circuit "B" serves Room "B" and has a unit load of 30 Btu/hr/ft2, it may require a 125 °F supply temperature. If both of these circuits are connected to the same manifold, the manifold must be supplied with water that is at least 125 °F in order to satisfy Room "B". But this means that Room "A" is also being supplied 125 °F water, which is 15 °F higher than what it requires. This may mean that while the system is on, Room "A" will actually be delivered about 30 Btu/hr/ft2 of heat. This will cause Room "B" to become overheated unless it can be automatically turned off when the room set point temperature is reached, which requires the room to be zoned separately with its own thermostat.




You may be tempted to say that this potential overheating problem can easily be resolved by throttling the flowrate to Circuit "A" by partially closing its balancing valve (assuming that it has one). You would be correct, however in doing so you would no longer have a "fixed temperature drop" design. Reducing the flowrate to a circuit causes the temperature drop to increase, and the average temperature to decrease and the net heat output to decrease. See the Variable Temperature Drops section below for more.

Variable Temperature Drops
When variable temperature drops are specified, LoopCAD will attempt to balance the loads by throttling the flowrates supplied to the individual circuits (assumes manifolds with balancing valves).



To do this LoopCAD sets temperature drop for the most highest demand room to be equal to the Design Temperature Drop value. Rooms with similar load requirements and design parameters will then have similar temperature drops (i.e. the Design Temperature Drop). But rooms with lower load requirements, or different design parameters, will have temperature drops "higher" than the Design Temperature Drop value. Decreasing the flowrate supplied to these lower load rooms causes an corresponding increase in the fluid temperature drop.




The amount that the temperature drop can increase is limited by the minimum fluid return temperature, which cannot be less than the rooms set point temperature.

still Im not sure for design purposes which setting i should use with the fixed dt15 setting all the loops on design day are between dt 15 -20 except two loops ones 32 the other 49!

keyote

Harvey thank you for that i have some bellini flow switches kicking around that might even work. unfortunately here in NYC we got tinknockers and fitters and plumbers and controls guys and electricians and commissioning agents and mechanical engineers and half a dozen others all do a little bit of these big jobs so even with thousands of coordination meetings etc im not an expert on the other guys work whereas tinkocker in a little town does the entire system but its a simpler system i only know enough to get into trouble it seems.

keyote

Hot rod so i un locked the DT 15 and what happens is 10 of 15 loops are DT 39-57 and the rst DT 15-10 i know the mods like cool return water but i dont get how that jibes with radiant supposed to be dT10-15. and though it changed all my total head to 4.7 and flow 3.9 on design day so now im probably off pump curves on the low side on non design days. i will read that idronics 16 maybe ill get it there

hot_rod

Don't worry about getting the exact supply temperature or exact ∆T to your loops or zones. If the ∆ moves a few degrees from design on some days or under some conditions, so what; the world is not going to end. Comfort does not stop, efficiency does not go into the toilet if that happens.

We talked about keep zones together that are with 15- 20° of one another, don't over complicate SWT requirements. Fine tuning can be done at the manifolds for flow rates, the boiler, especially with ODR will take care of supply temperature corrections.

Until the spaces are occupied for a heating session or 10 it is hard to know exactly where the sweet spot is. Keeping in mind all that design sweat and tears is based on a best calculated estimate, there is no absolute to a load calc or system design.

Six designers could come up with 6 different load numbers, it could be info input, the program they use, the assumptions for expected weather the next decade, or unknowable infiltration assumptions. Maybe the winter of 2016 will be windier that normal?
Maybe the tenants do a lot of entertaining and doors open and close often, your AC/hr. is way off. Maybe they drink a lot of beer and the refrig runs non stop dumping heat into the space

That design ∆T is just that, a design point to calculate from, if you settled in on 15° design and you find the system operates at 17.5° ∆T, what will you do? Remember that thermal equilibrium discussion.

I'm all in for optimum comfort, all for highest boiler efficiencies. Go condensing, go ECM circulators, embrace ODR, spend money on getting the loads as low as possible. All these are easily doable.

keyote

Thank you hatteras yes that makes sense i thought perhaps the pump would not operate so it sort of jumps up to the band in effect it has a minimum wouldnt that give the boiler its 1 gpm due if there were a by pass, taco says you can adjust that variable curve band , BTW i believe sitting on buckets and observing reality has advantages reality trumps theory when they disagree, and i have observed they disagree more than we expect.

keyote

Hot rod thanks again for the idronics going to try and read them all though i admit i skimmed a lot of the formulas, but it did help clarify these DP ecms And i kind of see how a DBPV is redundant but a bypass pipe or instead of headers complete the loop i think is still good, i say this because what the article seemed to say is you program the pump for wide open design day and it then adjusts down when it encounter less than that resistance, so i would think if i simply program in a bit more than need be enough to drive a gallon or two through the boiler on a bypass loop then the pump doesnt know its tricked it just thinks the last zone to close is a little bigger. As i type this im thinking but all ive done is overpumped, how bad is that if the boiler has almost zero head loss am i really needing to pump much more is this just gibberish because im not fluent enough to think of half a dozen things that are happening hmmnm

Gordy

I have to laugh at times in how complex we believe we must make a hydronic system to make it work.....

I have over 3400 square feet of living space supplied by ceiling, and floor radiant. Some rooms have both. One zone, one pl30 circulator delivering to 27 loops parallel piped. 5000' of copper.

My system delta is always the same at approaching set point. No matter the outdoor temp. 15

My loop deltas vary from 5-15.

The boiler is oversized 210 k heat loss is 75k by the program. I think more like 60k yet never cycles off high limit. Never fires for less than 10 minutes on a call.

Anyone care to note why that is?

And oh yes it's been in service since 1952. Still the same taco paneltrol mixing valve that does its job.

Harvey Ramer

That's because your emitter system is able to deliver btu's probably almost as fast as they are produced. Copper pipe embedded in plaster or Concrete will suck heat out of the pipe like greased lightening. Pex is a different mule. More thermally constipated.

Gordy

The monkey on the back that modern tubing has given us. The btus can't jump off the train, and make another lap constipation gets moved to the HE boiler.

Gordy

Mass,tube density 6" on center in ceilings, and low approach time to thermal equilibrium also. I don't use setbacks.

keyote

yes but im seeking to have the simplest system possible one pump to rule them all

Gordy

Subliminal message sent.....

keyote

;]