whats are the design goals DT, water temp, Flow, Etc

keyote · July 2016

Hey Guys So I finally did the detailed heat loss in Loop cad. I have the whole 4500sf flour story house im renovating in Brooklyn ny drawn up and circuited out. [ the top floor i have installed loops manifolds and risers down to cellar having done the calculations in my head years ago when i started]
so since i now have tenants on that top floor who will be wanting actual heat this winter it was time to do the calculations and design and install the boiler and trim.[they each have a tankless for for DHW so they have no idea lol]
Good news is it seems my calcs were ok for that floor and the total loss for building will be a less than i thought so i guess the triple panes and spray foam etc will do what i intended.
Heres my question. The loop cad says 47-52 kbtu for a 4500 sf depending on how I mess with the parameters. My biggest concern has been floor temp because 85% of the floors besides basement are 3/4" tg oak over 3/4" sleepers and 1/2" pex on top of 3/4" sub floors.I think the max floor temp should be 80 degrees? my exterior walls are 13" of brick and 2 1/2" closed cell and 5/8 rock i plugged in 17 R. so it seems i can change DT etc and still end up in the biggest glazed rooms at about 78/80 needed and about that available which i suppose they are referring to design days.So if I am understanding what im doing [which is not quite true, i have some latitude, and want to know where I want to dial in this loop cad program before my 30 day freebie runs out.
Theres going to be a trade off im guessing something like lower DT and temp more pump electricity?
Which Im guessing will have to do with loop lengths and head loss so ill just say i put a 1"SS manifold on every floor fed by its own 1" copper S/R riser each floor has four loops 174-225 though i have a couple of 250' and a 300 and a 350 sorry.so i think i have minimal friction.I could look it up. [and as I said I havnt done anything in the cellar though i bought a used triangle tube prestige 110 and indirect which i plan to use indirect foe the 4 baths and kitch on the owners triplex] In fact im a but confused on how i should be piping this but thats another can of worms first the detailed heat loss right.So im just putting it in there to help with how to dial in the loop design.
Thanks guys I love reading this blog. Im a tinknocker BTW but Ive built a few houses etc.

Boon · July 2016

I think the max floor temp should be 80 degrees?

As a non-professional, I can't speak to best practices in the real world; however, Siegenthaler's Modern Hydronic Heating, 3rd edition recommends a max floor surface temp of 85°F for rooms with prolonged foot contact and that for bathrooms, hallways, entry foyers the temp may be increased as high as 92°F.

im guessing something like lower DT and temp more pump electricity ... so i think i have minimal friction.I could look it up

Without dialing-in the piping, temperature(s), flow rate, head loss of piping at flow rate, distribution efficiency/operating cost is all a guess - for me, anyway. I never used Loop CAD but I assumed it calculated all those variables.

hot_rod · July 2016

For radiant floor comfort you want a 10- maybe 15°∆T so the temperature across the panel is somewhat consistent.

The max surface temperature has to do with comfort, above 82- 85 it becomes too hot and you may experience sweaty feet.

The key is to cover the heat load with the floor surface at a reasonable temperature, some suggest 82° max.

One rule of thumb is 2 BTU/ square foot for every degree difference. So a panel surface temperature of 82 minus room temperature of 70° = 12X2 about 24 btu/ sq ft. Most agree a comfortable residential radiant floor is limited to about 25 btu/sq. ft, before you look at adding supplemental heat of some sort.

Also keep in mind the amount of available square footage to transfer that energy. Space under cabinets and appliances and some furniture needs to be subtracted out, know a heat flux.

How does that 24 btu/sq. ft. number match the heat load number you came up with?

Panel rads can run as high as 30∆T, fin tube generally 20∆T design.

You may not require 1" S&R to all the manifolds, depending on how much energy each manifold is transfering.

keyote · July 2016

Boon
I have always been curious about the people who feel a need to answer internet questions they know nothing about. I suspect you tell yourself you are being helpful. You are actually polluting the stream of distributed information with sewage. What you are actually doing is trying to glorify yourself on the coattails of people who have put their lives into the subject at hand-You know, the people we come to this site to seek advice from. But your useless garbage will now permanently be included in any search of this site as well as the internet.

The internet could be a great way to find out even how to build a rocket except that 99.9999999999% of the information is from non rocket scientists feeling the need to signal intelligence. Maybe you actually are a professional at something if you want to be a internet superhero go to the website giving advice in your own field and feel free to raise the level of discourse. And please delete your comments on the way out.

As my post made clear I am actually an HVAC professional [30 year as NYC a tinknocker foreman] who has built several houses from the ground up , and so has extensive plumbing skills,including adding radiant zones from the ground up and has just mastered an autocad mechanical software program, because I am familiar with autocad from sheetmetal drafting.

And yet I am asking my colleagues for help with dialing in an aspect of the business I am less familiar with, on a website that is run by the best guys in the business to benefit those who have suffered bad plumbing advice and service often from actual "plumbers" you are not even a plumber a bad plumber an apprentice plumber, why on earth are you commenting? You are making this site like the typical advice website.People like you ruin the internet. Yes I have Siegys books [and software] and shelves of construction and engineering books,what you are referring to has nothing to do with wood floors specifically.And I have read dozens of articles about radiant and wood floors i want the opinion of the guys on this section of this site because as a professional i recognize when someone actually knows what they are talking about rather than what they heard or read somewhere.I dont even understand what you were trying to say about the parameters i inquired about. yes Loop cad calculates how they interact with each other and so if you change one they all change the question is a complicated one but its what are the sweet spots trade offs and diminishing returns between surface temp[on hardwood] water temp delta t flow pump electricity.As I pointed out in my question I already have tried several combination that all provide good performance But realize that means I am close but not dialed in.

While on this site [and others] please please confine yourself to asking questions and reading answers from professionals. To be clear though technically I am a " heating professional" being an HVAC mechanic, I recognize this is primarily a plumbing and steam fitting site. and so I in no way represent this site or its membership and speak only as a citizen of the internet. Im sure they welcome the traffic but if you degrade the site their will be no traffic.

keyote · July 2016

Hotrod
Thank you so much for that This software is great when its working but gets a bit buggy, not updating temporarily losing info or sending errors. but it always seems to work it self back eventually though the interim is scary. wish i could afford to keep it just for kicks, though it definitely needs some improvements.

So like an idiot I wasn't really thinking about DT in terms of uniformity, more about system efficiency with boiler pumps etc.. Which I think is why i was getting hung up.

I did assume DT 10 would be most efficient and so used that setting; at which the loop info boxes give GPM all between .75 and 1.0, The zone [manifold] flow rates are 2.5, 3., 3., and 3.5, there head losses are between 10 and 20.Thecircuit info boxes have another notation im not clear the meaning of, it reads. DT:10'F[MAX:---] ---- usually reading about 10-12 degrees. I think its telling me down to what degree day it will function? if so thats good NYC is a 17/87 design area.The water temps seem to be 106-123. The water temps are 106-123 degrees,the total head loss is 21'

The room 'BTU SF loads' are all between 10-15 except the top floors two large end rooms which are 17 and 21 btu sf load. It has a box in each room that gives 'required' and 'actual surface temp' [which im obsessed with because hardwood floors] they are almost all at 78-81 degrees almost all the 'actual temps' being the one a degree or two higher.
theres 3800 feet of loop and its a 4600 sf building and calculates total load at 51,000.

I ran the S/R risers up 27' from cellar to top floor manifold in 1" because I have two capped off zones which i hope one day to feed a 400sf penthouse addition and thought 3/4"copper or 1" pex was pushing it to save a hundred bucks on pipe.And I admit I have been planning to use 1" to the other manifolds because i like to over build, and its only total of 3 sticks, and im OCD and like it to all match, so Id need a good reason to not do that like it will actually degrade function ironically i have some taco circulators in 3/4" which might work so its really not just the pipe.

But Im unclear how i am going to pipe this in cellar I mean primary secondary and al, but one or two pumps, and zone circs or zone valves, Still researching.
controlls is also in research. i pretty much have a loop for every room except the bathroom would be on the same loop as it bedroom halls etc i usually pick up with the leaders so id like to control every room independently,I think its a matter of putting an actuator on every loop and wiring the thermostats to them [well through the control panel] Im liking the honewell wireless thermostats and control systems with red link partly because im a control freak and partly because its worth a $1000 up charge to not have to figure out how to put in the thermostat wire i forgot in the finished and occupied apartments top floor.

right now the lower three floors are heated with an atmospheric dragon in 100 year old asbestos pipes but Ive started work on the next to top floor and hop to add it to new system within the year.but i will be putting the indirect DHW in now

keyote · July 2016

Oh and I am considering adding a snow melt in the future anyone know if they rt really work and if they are ridiculously expensive to run thinking in old age and retirement travel tenants and city will insist sidewalk is cleared. its only a 20/12 sidewalk, a 20 /8 porch and maybe a 10 /70 driveway

hot_rod · July 2016

So it comes down to how much $$ and how complex do you want the control to be.

I'd guess you want at least a zone on every floor? Maybe some subzoning depending on how the home will be used. At least zone off the master bath, that is a nice touch, and the controllable radiant area my customers rave about the most.

If you are using nice radiant manifolds, like Caleffi, you can always add actuators and break down more zones in the future if you desire. Install the loops accordingly to allow for future zoning.

Adjustable flowmeters on the manifold allow for manual balancing and possible eliminate excessive t stats around the building. You would need to run thermostat wires to potential zone areas. Unless you trust wifi actuators

Manifolds with ECM circs attached are available also.

It sounds like you could get away with a one temperature system to eliminate mixing devices, if all the zones are within 20° of one another.

Maybe LoopCad allows you to tweak the supply temperature number, and show a change in tube spacing to accommodate similar supply temperatures to all the zones?

You only get one chance to tube the place, tighter spacing = more consistent surface temperatures and lowest possible supply temperatures for best efficiency of condensors.

A mod con with ODR at least, indoor feedback can be nice if you plan on entertaining, with wide and varying occupancy loads.

Once you select the boiler, the related piping will become more clear. The recent higher water content type seem to be the rage. Lochinvar, Viessmann, Laars, HTP, Burnham, NTI, many many good choices.

The snowmelt would prefer to have a dedicated boiler, don't be tempted to size one boiler for the home and snowmelt. Plan gas piping and venting if you will add snowmelt. 1000 sq ft of snowmelt could cost you another 100,000- 200,000 BTU/hr boiler depending on how quickly you want snow to disappear.

If you have a large DHW load, the snowmelt boiler could be kept busy year 'round covering that load so the home boiler could always cover heating only.

Boon · July 2016

Hi Keyote. I meant no disrespect. I saw a small portion of your post contained a question that I could answer. I was careful not to misrepresent myself or my experience with radiant flooring, I cited my source, and, yes, I sincerely suspected I was being helpful and contributing to the site that has helped me so much.

keyote · July 2016

Hot rod do those numbers seem good or would you like to see one of them raised or lowered, what about maximum wood floor temp I had it set to 80 degrees. I am a bit limited because as you said you only loop once and the top floor is completed, in retrospect I might have gone with 10" instead of 12" spacing since its got at least for now a unconditioned crawl space above it. I did just try raising the max floor temp to 81 and 82 degrees which raised water temp to 127 and 129 degrees but that seemed to over heat the other rooms too much.A couple of the biggest rooms have the most glazing. honestly Im probably making too much of it the top floor had the biggest discrepancy between rooms and it worked out to be the two big rooms were one degree short of perfect with the interior rooms all a few degrees over spec.The rest of the house since it wasn't yet actually looped i balanced to top floor by loop layout.But I think actuators will solve this minor problem?

As I said as it works out I pretty much have a loop per room I bought the reifing manifold for the top floor which was very reasonable it has manual flow adjustment but will accept several brand actuators, which im at this point vague on I think of them as mini zone valves that would allow some loops on a manifold to get flow/heat and others not. at only $30-45 a piece plus a $125 wireless thermostat, its $700 a floor, Not cheap but I think worth it control is important because its a three unit building and 4 floors so usage varies and Im away a lot and have house guests erratically so occupancy varies a lot.and Im only doing one floor at a time so cost is spread out. I can still run the actuator wiring without any trouble so would only be trusting wireless on thermostats i liked this honewell system because its red link wireless band supposedly is a commercial grade radio frequency system not wifi per se and it also links to the web for remote access.and its actually less expensive than the radiant specific brand but interfaces with taco etc.

I ended up getting a great buy on a slightly used TT110 which came with their indirect tank and a bunch of trim some new in the box. I needed to get the heat functioning for the tenants even though the rest of building is on old system. and didnt want to invest too much or risk damage until I was more sure what was needed, though i thought i would eventually end up with the new model TT110. as it turns out this may be too large maybe the TT60 though they all claim they can MOD down to 25% so how important is the exact match?

But I haven't gotten clearer on the install.
I have looked at the TT install pdfs as well as read numerous threads about installs on this site with all the critiquing of tee spacing etc LOL. and Ive read pumping away and P/S made easy, skimmed sieggys book and will use his software to size the circs etc so Im vaguly aware of some things but.

The thing is TT shows three different versions of a multi zone radiant with indirect DHW system, so im not yet concerned with the minutia of the trim yet, but whether i want a one or two pump primary loop, whether i want zone valves or circulators to the manifolds whether im ignoring the internal TT circ pump and control box in the TT. whether my choice of controls will effect those decisions.I know it sounds like im off half cocked but I like to think of it more as a just in time approach you see i have been single handedly gut renovating this huge building while working full time and so I research far enough and deep enough to not work into a corner then pick it up again at the next phase of construction.Oh and Im building an airplane and its engine in my spare time. -Did I mention the 21 year old.

sounds like this used TT110 could end up as the snow melt unit i actually got a second indirect that was completely unused so i could put the two old units into snow melt after i get the final boiler. Im going to try and leave piping wide enough swapping boilers will be easy

I have never heard of this 'higher water content' type of boiler.

hot_rod · July 2016

If part of the system is installed already, you are tied to the supply° required for that area at design condition, unless you add supplemental emitters.

If you are comfortable with that 51K load number I'd consider the Lochinvar KBN80. Net output of 64K puts you real close. It has one of the nicest controls out there with three temperature controls and three ODR function, very adjustable with ramp delay and more.
You may or may not need or want that much control logic, but more often folks that buy too basic of a boiler and control regret the decision.
With the high water content, 18K low end and ramp delay function it should be a nice fit.

I have yet to install this model, I think you could eliminate primary secondary or a low loss header.

The 110 may be a tad light for all that snowmelt, it could be zoned and prioritized however. I have seen driveway snowmelt system run with a standard gas fired water heater!
It's a time and temperature game, melting snow.

keyote · July 2016

Thanks Hot Rod I will look into that and similar boilers I am definitely wanting as much control as I can get without being stupid. So do you think my numbers are good where they are at? whats your feeling on wood floor temps?

hot_rod · July 2016

This is probably some of the best data on the subject of wood flooring and radiant, thanks to Robert Bean for providing this and so much more at Healthy Heating.
Usually when ASHRAE gets involved in a project or topic it is pretty well researched.

http://www.healthyheating.com/Thermal_Comfort_Working_Copy/Definitions/floor_temps.htm#.V37Uclf6S-I

The RPA Flooring Guides, over the years have also provide great info.

Mickey Moore is another expert I met through the RPA that has written extensively about wood flooring and radiant.

http://www.fcimag.com/authors/1898-mickey-moore&sa=U&ei=sgxPU_jIGYjAtAaF-YCIAQ&ved=0CDAQFjAE&usg=AFQjCNGnCR5OwCE4HKzh9j6Ou66LM0x4pA

Remember, humidity control has an awful lot to do with wood flooring health. Are you considering any humidity control and IAQ in general?

These days it is more about comfort systems and less about heating and cooling systems. So many good products to help address both.

Snowmelt · July 2016

I did a snow melt driveway in my moms home in linden it works well. if you want I could help you designed a system. prices cant be chatted on here. give me a private message and we can talk.

whats are the design goals DT, water temp, Flow, Etc

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