Hi-eff GFA + sep. Tankless DHW vs. NG mod/con RFH + DHW combi?

CA_Craig

Been lurking here awhile, thanks to your collective wisdom and sincere helpfulness!  

Doing a renovation of a 1926 flat roof Spanish-style home near SF Bay, with 2-story 1990 addition.  No existing systems - need new DWH and Space Heating.  Previous have been gutted/removed.    Building is effectively a wood shell w/stucco.frame ext.

 

Trying to figure out if I should stretch my limited budget to reach RFH space heating, or just get over it and do GFA.   I have a couple more days to decide.  Yea, I kind of "researched"  for a little too long!  Oh well, here we are.     I can get designs and quote from local distributors, but I am concerned that they will try to "push" me towards their lines without pointing me towards the best system for my space/use.  

Since I have about, uhm, 1 day to pin down 2 best options so I can reach out on those locally, anyone care to give some input as to what  my "top 2" system design options might be?.



Parameters:

* Footprint is 1160sqft, the 2nd floor of 1990 addition is 350 sqft over that. 

* 2102 Renovated Main structure 1-Floor: 810sqft (18'x45') 8.5 ft ceiling, walls 950sqft less 113 sqft windows, 1-3/4 inch wood slab front door, over an unconditioned basement. 3/8" Hardwood floor, open concept living/dining/kit, 1 bedroom, bath, laundry room

Ceiling/Attic (2' attic space, flat roof): R30 cellulose blown

Walls: R13 (recycled blue jeans sprayed)



* 1990 Addition Floor 1: 14x25, 8' ceiling, over insulated crawl w/slab, 2 rooms, 4 windows 4x4, 1 sliding door 6x6'8, 1 ext vinyl insulated door, 3/8" hardwood floor

* 1990 Addition Floor 2: 14x25, 8' ceiling, 2 rooms + bath, R30 attic, R13 walls, 3 windows 4x4, 1 window 2x3 (bathroom), 2x4 velux fixed skylight, 3/8" hardwood floor



Windows: Milgard Tuscany Vinyl Hard-coat Low-E (no gas fill)

Heat loss was calc'ed for GFA furnace at approx 48K BTU.  If I insulated the basement cripple walls, that could drop.

House gets decent passive solar exposure in season.



Groundwater temp: 57-62

Might like 2 zones (1 down, 1 up) plus DHW



Heating season low outside temp: 25 deg F (touches this once maybe every few years)

Heating season avg outside temp: more like 50 deg F



Given that we're insulating well and the reno will be fairly tight, I suspect that we would not need a very high water temp to satisfy space heating needs at design temp when system is running optimally.

Desired DHW flow:  4.8 GPM



Possible systems - mod/con would be best?  what will work best from a value standpoint?



Rinnai Q80SN + indirect (Thermo2000 Turbomax Reverse Indirect?)



HTP Versa-Hydro 130-55 (10:1 turndown on the space heating, 3:1 turndown on DHW burner)



Or:   Manifolding/banking two Tankless, one for DHW and the other could have a controller for an external recirculating pump (closed loop):  Rinnai RU80e-N,  Type of Controller MCC-91-2US (per spec sheet, optional for Commercial or Hydronic Applications) Seems less costly upfront but Is this possible?



I can install Pex + Heat Transfer Plates, to save cost, if an installer would do the other system components and tie-ins.



What are your thoughts?   Just could use a push in the right direction -- which distributors/mfrs to focus on?    With emphasis on value/bang for the buck.  (I know that cheap is not an option, but for the demands I have, there has to be a "good value for what I need the system to do".)



Thanks for any advice you can offer!

SWEI

a few more questions

Radiant will to provide better comfort, better air quality, and lower energy use than forced air.  It will also cost more - the differential is highly job-specific, so you'll need bids from qualified contractors (the qualified part is critical) in order to make an informed decision.



25F seem like a low design temp for SFBA?



Is there any cooling load?

SWEI

boiler selection

If you decide to go with radiant floors and you want to do some of the work yourself, I'd suggest either picking a manufacturer and letting them do the layout, or paying for a stamped professional design that you can use for permitting.



Assuming you decide to use a gas-fired boiler, I'd choose a fire-tube heat exchanger design (Triangle Tube, Lochinvar, and a few others now have these.)  They reduce the system complexity by allowing direct pumping, require less maintenance, and are more tolerant of hard water (not an issue in most of the SFBA itself, but in the surrounding mountainous areas it can be significant.)

VictoriaEnergy

The Forced air option

The house isn't big, so if the layout options for the duct work are favorable, a forced air system could also be a good option.  The big "if" is the ducting, can you locate the furnace near the center of the house?  What will be involved in getting heat to the upper level?  If the furnace has to go in a corner under a set of stairs or in the attic; forget it.



The quality of the furnace and installation makes a big difference too.  We recently installed a Bryant 987MA (Same unit available under Carrier brand) modulating furnace that mods down to 40% of full firing rate depending how far the current room temp is away from set point temp.  Operates at it's peak 97% efficiency all the time.  Faster recovery from nigh time or away temp setback.  When running in the lower end of its BTU range is runs VERY quiet.  Easy to add air conditioning, air filtration or heat pump in the future.  Installed cost and ongoing maintenance cost is lower than RFH.



RFH is widely accepted as the best heating system available, and I agree.  On the other hand; the best forced air well installed in small and mid sized houses can certainly give RFH a competitive option at way less cost.   

C_Craig

Yes, I'm in Oakland.. So design temp maybe more like 35 i guess

Sorry, not sure why my first account doesn't work and won't reset pwd, so here's me in a new nick.

VictoriaEnergy, the GFA system planned was a York Guardian 95.5% single-stage 60,000 BTU high efficiency furnace (non-modulating, so it won't run nearly as seamlessly as yours does!)..  It will be suspended in the crawl space via unistrut near/underneath the weighted-center of the conditioned space.  Because the house is fairly compact, the ducting is pretty simple, and the runs upstairs are more vertical than horizontal from the plenum.



SWEI, I'm not doing anything to cool the house (since we replaced the windows last month, it has never really gotten hot in there, and that's without any insulation, or even a ceiling).  I don't have data but the city water does not seem particularly hard and I've lived here for 13 years.   So that should not disagree with the TT HX.



I'm okay with picking the manufacturer and letting them do a design that I can install the tubing on - if it makes permitting easier, that's value.  I did all the renovation permitting myself to date and I'm frankly pretty tired of it!   Now I know why my GC was like, "sure, if you can pull the permits, that will make things easier..."   I suppose, in a way.



With the TT, would I be installing an indirect for DHW or are you thinking Challenger combi and that's it?  on the DHW flow, I really wanted to get close to 5.0 GPM (want the design to allow for 2 showers and a kitchen sink faucet running - not often but possiblity exists).  Not sure how to design with a TT for that.  With an indirect for DHW, if there's a DWH call, will it totally stop the space heating supply?  I think that's how the PE was?

SWEI

sizing

Properly modulating forced air systems work great, but are unfortunately somewhat rare here in America.



Whether you realize it or not, your 5 GPM requirement has a time component associated with it, and this is where the indirect sizing happens.  Tankless water heater manufacturers like to focus on "forever hot water" but it comes as a cost both in terms of both initial expenditure and turndown capacity.  Real-world domestic water heating almost always benefits from the proper marrying of BTUs to storage capacity, so spend a minute with an online too like http://www.statewaterheatersizing.com/ to understand what your real requirements are.  Then look at your IDWH manufacturer's specs with the boiler you are buying and see what you actually need to buy.  Or just hire a truly competent professional and get the job done right.

C_Craig

Is my demand low enough to use Tankless controlled for RFH

because the Rinnai RU98e condensing tankless unit specifically says to use "controller MCC-91-2US (optional for Commercial or Hydronic Applications)"?   The input on that unit modulates 15,200 - 199,000 BTU. 

Could this be used with a Taco X-Pump Block to create closed systems for DHW and Space Heating both served by the properly conrtrolled RU98?  



Thanks again!

SWEI

re-run your load calc with the correct outdoor design temp

And see what the load looks like.  Then remember that you're going to need less than that 97.5% of the time.  Turndown ratio is a challenge with NG in mild climates.



The RU98e is a 199,000 BTU/hr unit - not sure how efficiency fares over the turndown range on those.  Choose something closer to your actual load.  The E75C fires at 75k, but it (like all the Rinnai boilers) requires primary-secondary pumping.



A Lochinvar WHN055 would probably be my choice for this.

C_Craig

thanks, i'm doing that and having a radiant pro designing

a system around a Rinnai Q85S boiler + :Lochinvar Squire 40gal indirect.    He thinks I would be fine without the indirect, only the Rinnai E75C combi (around 2.5 GPM on dhw), but I like the capacity added by the indirect for multiple domestic calls at once.  The 40gal Squire only loses about .9 deg. per hour.   How does that sound?

Another contractor wants me to compare that to a design he did around a Takagi unit - he says it includes a boiler.  I may stop back in and see if you can give me feedback on that comparison.   I really appreciate your time/guidance.  Thanks!

Jack

Another option

Given your open floor plan and small upstairs space, I would suggest you look at the Rinnai Energysavers. An EX11 upstairs and perhaps two EX22's on opposite walls downstairs would give you more than enough capacity. You could do the downstairs with the one EX38, but I prefer the zoning capability of the two smaller units. All are net to the space with no distribution system, quiet, cool to the touch, modulating burner and blower, built in programmable t-stat and are a simple install. I live in Nevada City and heat 1400 sq ft with two 22's. Both are downstairs and I like the bedrooms somewhat cooler than the primary living space downstairs, but they are only about 3* cooler. With that, your choice of the 98 tankless will provide 5.3gpm at a 70* rise at a .95 EF...all day long. The RL94 will do 4.7 gpm at 70* rise



The Rinnai tankless for space heating...in an open loop system works, but in my opinion would be the last of options you list. I do not like tankless for space heating. They work, but it isn't what they were designed for. You want to do this once. Therefore, use equipment for their primary design spec. The tankless space heat option is cheaper, but that is all it is! In the good, better, best world tankless space heating is somewhere below there;)



The Rinnai Q80S will modulate from 17-80kbtu. The unit requires primary/secondary piping, but is supplied with the low-loss header and the internal variable speed pump. Should you choose the boiler and an indirect there is a three way valve option that can be mounted on the boiler which allows you to use the boilers internal pump to drive the indirect.



Now, in fairness, I must say that I represented Rinnai in New England for a long time and am working with them now in a consulting capacity, so bias noted.

SWEI

Good to see you here, Jack

I was sort of hoping you might stumble in.  While you're here, can you shed some light on how the different Rinnai lines are designed/used?  Glad to see the wall-mounted boilers now, but they do make an awful lot of models.

C_Craig

the EX11 and EX22 sound interesting, but I have a

Special issue:   I am doing this rehab with a kind of construction loan and bank-approved plans are for central heat.   The living/dining/kitchen areas are open concept, but there is also a 12x5 bath, 9x15 bedroom, 5x5 laundry, 11x14 family room and 9x14 second bedroom downstairs.  Although the house is only 18 feet wide inside, it's 70 feet long and pretty broken up, so I am not sure if 3 or 4 space heaters would cover everything, even if I could get it past the bank.



The Q85S+Squire plan came in at double the cost (can i say that?) of the modulating York 97% eff mod/variable gas-forced air furnace plus tankless dhw installed.  I really prefer the radiant but need to knock a lot off of the cost of it.   I already have 20K more than expected on credit cards because some unexpected structural/dryrot issues made mincemeat out of my budget, and since I had (have) no cash to give,  I needed to take on extra fixtures purchases on credit cards to cover the over-budget work needed.  The house will still be worth more than what I will owe, but I just can't keep spending extra $$ that I do not have.   As it is, I will need to figure out how to put about half the cost of the radiant system on a credit card.



Going with an E110C gives me the dhw flow I want but the space heating only modulates down to 26K BTUh.  Since our winter temps are usually 43-53 F (sometimes in the mid-30's at night but not often)   I might fairly often need less than 26K.   The York GFA mods down to 21K.



Can either of you think of another system design that would be sound and effective but not stress me too much in cost?    I can use a tankless with a Taco X-block, if that saves enough.   I also need to find out how to use less heat transfer plating - the design I was given put those alone at about a third of the total system cost.   The flooring above the pex tubing is supposed to be hardwood (except for tiled bath floors).



Maybe I could pay a system designer to do design/layout, then I could DIY install the tubing, and I know a plumber with radiant experience who would give me a good deal on the install as well as being there for servicing/adjustnents if needed.



Thanks again - I really appreciate it!

craig

C_Craig

since my winter temps outside are around 40

and I am insulating well, would it be okay to widen my pex spacing?  Say, 16" O.C.?   That would be one tube per joist bay, and then use extruded AL heat transfer plates?   Are some of those plates wider than others?   As long as I can keep my floor temp under 85 F (hardwood floors) would this work with the Rinnai E110C?    I don't live in MN, Ontario, or Alaska.  Also, since the upstairs is above a space which will be heated already, I could perhaps do half coverage on the heat transfer plates? 



What about Ultra-Fin?  That might be a good solution on the heat transfer method?



I found a local supply house (Pace Supply) that carries both the Ultra-Fin system as well as the TT PTE110, fire tube combi.  Likely a more appropriate sized boiler for the load and I like the 14gal buffer tank built in.  Thoughts?   Much appreciated!

Jack

Not sure where to go with this one

Heaters/water heaters? You have to be careful what you ask as I may end up writing War &Peace;) On the heaters, I just think it is one of the most undersold pieces of equipment in the business. I've sold over 180k of them in New England and am working them out here in CA on a part time basis. Apartment building conversions, straight residential as supplemental or whole house heating, basements and garages are the primary applications. I heat my house with them. fantastic product and another tool in the tool bag for a heating contractor. Most here are "system" guys and hence they do not get the play, but they are one of the best pieces of equipment I've ever seen.



Rinnai have gone to the Value, Luxury and Ultra categorization on the water heaters. Value are small residential and builder models to a price point. Luxury ( my favorite) are the .82ef units and ten the Ultras are the condensing models at .95, .96 EF. They are doing the residential of course, but more and more commercial as well.



Any specific question I'll take a run at!

SWEI

so many lines

It's clear that these are boilers http://www.rinnai.us/boilers/



It's less clear what the intent is for TWH models used as boilers.  Things like "Controller MCC-91-2US (per spec sheet, optional for Commercial or Hydronic Applications)" merely add confusion.  I don't see a spec sheet or I&M manual for that controller online, but perhaps I'm looking in the wrong place.



Short version:  We get people here every week or so proposing to heat their houses with water heaters (whether tanked or tankless and it would help to understand Rinnai's position with regard to application of their equipment.  Do we point them at the boilers and say "that's the right way to do this" or do we acknowledge that for certain applications using a TWH is just fine?  If so, which applications?  Is there a duty cycle issue?  What about turndown rates and ORC on tankless?



thanks...

Jack

Back on topic

The Energysavers are tested and approved as Wall Furnaces and therefore comply with bank financing requirements. If they were simply "space heaters" you would have an issue. I think you will find that a unit at either end of the first floor will do nicely for you, but I have not seen the plans. Tjernlund.com makes a "problem solving fan" called the Airshare. Check it out. They are excellent!



You have discovered the limitation of combis. You select for DHW requirements and end up with to large a heating boiler in some cases. If you go with the heaters, go TWH. All of the Rinnai boilers have a 3" low-loss header. It provides a pretty good buffer against min flow rates. The boiler loop looks for a 36* temp rise and the house loop does its thing. The reset curve on the Rinnai boilers is very flexible. The Q80S will modulate down to 17k, but it is heat only and you can add the indirect or TWH.



I have a real problem with duct work. In fact when I moved into my hosue here in the foothills I tore out a 5 yr old central H&C system and went with the Energysavers. Should you choose to go with the York system you should demand in the contract that the system have "no leakage". CA permits up to 6% leakage on a new system. I'd demand better. Remember, you are talking day one leakage. What happens down the road. My feeling is that all of the unitary manuf (York , Lennox, Carrier, etc) can put all the technology they want in the box. They just can't deliver it! It is not the equipment. It is the distribution system.

I am a big fan of "net to the space" heating & cooling. Energysavers and mini-split heat pumps .



How soon are you moving ahead with this project?

C_Craig

I like the Idea of Energysavers and Airshare

and because I need to install heat next week, and the electric and plumbing roughs are done, and I need to have the entire job finaled in 5 weeks from now, I just do not have time for the tubing/boiler.  Would need to demo more ceilings and rework too much.  Plus, the tubing/ultrafins would interfere a lot with the new electric and plumbing in the joist bays (or the other way around, either way).   For the DHW I like the Rinnai RU80eN.  I hear you on the ductwork and am really resisting it --- I am just worried that I would need too many Energysavers to make it practical, cost-wise.   I could lay down heat under the cement tile floor inb the 1st floor bathroom, that might help that room anyway.   Let me see if I can upload a floorplan so you can get an idea... 



I found the Aireshare and it actually looks like it might be workable, particularly since most of my walls are still uncovered, or can be opened up. 



If you can see the floorplan attached, I think an E17C 16,700 BTU could go on the left wall as you enter the front door about 3 after the door along that wall.   Could mount a shelf over it and coat hooks above, might be able to make it look nice even.   For the bedroom behind the kitchen I could try to put an Aireshare just at the beginning of the hallway, keeping the heat moving from front to back of that room.  Based on my reading, those fans seem to work best when you can place them to create a sort of convection effect.   Can't use the wall between bedroom and kitchen because it's full of cabinets.  So, beginning of the hall might work, as long as that air is still warm enough.  In the rear room of the house, the sliding door had to be moved to the right corner of that room as you enter it from the family room, so the wall adjacent to that (under that right window) might be a better place for an EX11C, with an aireshare on the wall to feed the family room from the back room (which is a convertible/guest bedroom)..  Can't use the very back wall of the house next to the sliding door because that's where the bed will go.  Upstairs, I need to find out which would be more economical, electric floor or the E17C.   I can use ceramic tile which might hold the heat pretty well.  What would you think?   I can see what my Rinnai guy at Cal-Steam says tomorrow, too.  I have checked them out online and can swing 3 of those furnaces plus 3 or 4 Aireshares, figuring that they would cost a little more to get locally but I would have the resources/support of the installer/supplier if needed.

Jack

SWEI

I wrote a lengthy response last night which must have been edited. Pretty sure I saw the "successful post". I'll try again later.

Jack

I always caution

folks from buying to many Energysavers. Keep in mind, these units want to do two things. Number one, meet your comfort demands and number two, do so at the lowest possible input and fan speed. With the constant modulating operation of the burner/fan they project the heat much better than the single stage on/off type units you are used to. From your wallets stand point these are the ultimate in zone control. I would buy two placing one 17 or 22 in the LR, either next to the door, between the LR/DR or, better yet under the window looking straight down the hallway. The other would go in the family room. Under windows is an ideal location for these as that is typically a harder area to decorate and you need only a 9" clearance from the vent termination to doors or windows. You can rough-in a gas line for where ever you think you might have a cold spot, but you can define those spots and treat them both with Airshares and additional Energysavers, but do not buy excess capacity. You will be surprised how evenly they will heat.



If you put a unit in a bedroom, do not use the 11. Use the 08. Where these make any noise is on start-up. You get pre-purge, spark, gas solenoids kick in and burner ignition. It isn't loud, but it is annoying if it short cycles. Min. btu on the 11 is 5500. At 82% that is in the area of 4400 net to the space which is a boatload for a bedroom and the t-stat has to turn the unit off. The 08 is down fired 08 to 3000 btu min or about 2400 btu to extend the run time in smaller spaces.

C_Craig

The city says I have vent clearance issues

When you say 9" to the nearest opening, how did you come up with that?  I was down at the city inspections dept today and they said that since I am less than 4' from the neighboring property line (actally 2'8" from the actual house on the right (top) side,  these would be hard to place.  They also said that it needs to be 4' from any door or window, just like the Tankless do.   Is there something I can refer to in the latest CBC (Calif code) book for the permits/inspections dept that helps them see otherwise?  Also, the window looking straight down the hallway is unfortunately only 6 inches off the floor.   So it would be on one long side or the other, for the big room.  thanks!

C_Craig

The Sr Inspector said I was too close to next door

So I could not put the wall furnaces in on the sides of the house - not a question of proximity of vents, he knows they are cat 3 appliances and 9" is fine, but it's the side yard setback that is a problem.  He also says if I get a tankless for dhw, put it inside, too much risk of the neighbors hearing it so close to their house..



Can I attach a system compnent list for the Rinnai E110C and since you are a Rinnai guy you can see if these people seem capable?   The only way I can afford this is by doing tubing 16" O.C if fins are needed.  Or he said I could do some at 8" via staple up which will still hang below the subfloor.  Do you know what he means?   He said his temps were modeling out at 110-120deg with 8" centers - with 16 the temp goes up a bit but it's still under 140 degees.   He can do 5 loops, 3 down, 2 up, using 1 manifold with actuators.



Thanks Jack!

C_Craig

The Sr Inspector said I was too close to next door

So I could not put the wall furnaces in on the sides of the house - not a question of proximity of vents, he knows they are cat 3 appliances and 9" is fine, but it's the side yard setback that is a problem.  He also says if I get a tankless for dhw, put it inside, too much risk of the neighbors hearing it so close to their house..



Can I attach a system compnent list for the Rinnai E110C and since you are a Rinnai guy you can see if these people seem capable?   The only way I can afford this is by doing tubing 16" O.C if fins are needed.  Or he said I could do some at 8" via staple up which will still hang below the subfloor.  Do you know what he means?   He said his temps were modeling out at 110-120deg with 8" centers - with 16 the temp goes up a bit but it's still under 140 degees.   He can do 5 loops, 3 down, 2 up, using 1 manifold with actuators.



Thanks Jack!

SWEI

priorities

I'd spend my money on closer spaced tubes (with plates) and save the value engineering for items I could change out later.   I would eliminate the autofill & backflow preventer -- no need to connect a properly working system to the water supply, though you should check the system pressure regularly.  Gauge could be 0-30 PSI, which may be required by code.

Jack

TWH

by Rinnai are not approved for "closed loop" heating systems. They cannot pass ASME requirements and IMHO, never worked well in the field. As well, for the small number of sales they created an inordinate number of problems. Why compromise an otherwise excellent product reputation to get some systems out on the fringes.



Rinnai does allow the water heater in "open loop" systems. Those are typically a hydro-air system in an apt building. I'm not really a fan of open loop, preferring to keep my water streams separate, but I have to say they have worked well in that application. Those that I had experience with were all small loads.



The MC-91-2US controller you are referring to is the "Commercial Temp" unit. All the water heaters can reach 140*. To go over that you must purchase the Comm controller. On the 180kbtu systems you can get to 165*, the 199kbtu...185.



I go out on other sites and hear of people all the time who want to use TWH, for radiant jobs especially. Some manuf say it ok. My experience says it isn't a good idea and for years I got to see the catastrophes in a six state area. Tankless are designed to see variable flow and high delta T's. They are excellent at their primary task. For a pro to do these TWH closed loop systems you are really putting yourself in the crosshairs, imho. It's funny how customers forget how adamant they were for a particular system and if you agree to do it, well, you end up owning the consequences. ODR has no place on any TWH I am aware of. There is no place to interface that type control. If you need a boiler, there are plenty excellent choices out there;)

Jack

Do you have

24" from the other building? That is the clearance requirement for the heaters. For the water heater, I don't think the E model would be a problem, but it is worth consideration if you are right on top of the neighbors. As to commenting on the 110C list, please understand that the man who gave you this list is a licensed contractor in CA and he has to live with that system. I don't see anything superfluous in the list. He is on site and I am not.

C_Craig

Yes, 32 inches but I think I may go with

The E110C combi system and ultra-fins in joist bays with FostaPex.  The guy said if there are occasional obstructions in the bays which make using the fins not possible, I could staple up the pex leaving some space between that and the subfloor and that would be okay.   BTW he is not a licensed installer - he is the designer at the Rinnai/Lochinvar supplier/dealer.



I am just concerned with the energysavers that due to all the little rooms I have, I may have too many hot and cool areas of the house.





SWEI if I did double up on some joist bays with pex and plates rather than ultra fins, would it be better to double up closer to the return end of the loop?

Or will combining those delivery methods just keep my return temps hotter and reduce system efficiency?



Also I need to find a good and affordable local installer.   I have one but I am not really feeling as comfortable as I want with him.   If you know of a good one in Oakland CA, please feel free to let me know. 



It's just nagging at me a little bit, that if something goes wrong with the system, I am out of both heat AND hot water.

SWEI

plates/fins

I've never used Ultra-Fin, but the info I see on their website seems to indicate it uses convection to move heat between the tubing and the subfloor.  This introduces an unnecessary layer of air that would be better off eliminated.  Extruded aluminum plates are not particularly expensive, and when combined with a sprayed or foamed void-free insulation, provide highly effective heat transfer.  Lower fluid temperatures under that floor will increase both comfort and system efficiency.

C_Craig

Really, SWEI? The cost of the plates I was told

was a full third of the total system cost.  The plates were more than the cost of the boiler and the indirect combined...  If that seems about right, there is no way I could afford aluminum plates...  The ultra-fins are 1/4 of the cost of the plates... which is the only way I could even do the radiant system...  Maybe I should have looked at other sources?

SWEI

plates

One third of the total system cost seems a bit high, unless the price included installation labor.



Read this http://scholar.lib.vt.edu/theses/available/etd-01182006-011730/unrestricted/Performance_Test_Protocol_for_Radiant_Floor_Heating.pdf before you make a decision.

C_Craig

well that was a good read, thanks..

and I am left with the feeling that in order to do it really right, without pulling my subfloors up, i should use plates.  Problem is my budget for a combi system installed is only $9K and I am not getting anywhere close to that using plates.  I am just about ready to throw in the towel on radiant.   I need to see if the bank will let me swap out the central heating in favor of the energysavers, and if city codes would allow me to install them even though I don't really have any side yards.  I was not encouraged by the Sr. Bldg Inspector when we discussed them the other day.  thanks, though.  kind of bummed now.