Based on little action on the post I put in the Design & Planning section I thought I would post a similar post here to see if I might get some more help.  Thanks in advance!

We are right at the finish of our design phase and will be breaking ground shortly on our new home.

Home Details:

Stick built with 2x6 exterior walls
Mostly flat roof with 2 sections of metal sloped roof R30
Slab on grade with 2" foam under slab
Total heated 2700 sq. ft
Family of 3
Reverse floor plan - all bedrooms are downstairs, warmboard upstairs, open floor plan upstairs.
Hydronic radiant in floor heat planned.

Natural Gas Costs - Current PG&E Costs aprox $0.98 to $1.08 per Therm
Electric Costs - $.12 Kwh up to baseline of 565 Kwh $.13 at 101-130%, $.29 at 131-200% baseline (don't expect going much over 130% range in this new home)

We have lots of south and west facing roof space with zero or limited shading, but they will be mostly be flat roof zones.  We are in climate Zone 03 with 1400 HDD per year - a Northern California coastal climate with lots of fog in summer, afternoon sun is common most days.  No cooling needed.

We currently have a Lochinvar KBL150 boiler for DHW & Radiant heating on our preliminary plans

We would like to get a system that is ideal for our location and that has a low up front cost up with decent operating costs - would like a decent ROI if possible.

1. Use a single boiler (or equiv) as specified
2.  Use a smaller boiler - say a Lochinvar 50 along with an indirect hot water tank - running the radiant heat with glycol instead of shared hot water - plumb for future passive solar hot water to the indirect tank.
3. Use a hybrid electric water heater and connect with PV system (may not work as our DHW and heating needs are mainly in the eve and early morning)
4. Or something recommended by others here...

I can't find any decent local or state rebates that would apply to the new construction - future solar would apply as a retrofit and could gain us rebates from PG&E

Yes to natural gas.

Yes to condensing boiler.

No to glycol.

No to PV or Passive solar if ROI a concern.

Must start with a heat and domestic hot water load analysis before proceeding further.

with 1400 HDD I can't imagine a mod/con even makes sense. but my HDD map shows northern california at three times that. 1400 HDD is more like the border of mexico.

We are in a very temperate climate on the ocean - 95060 zip code - what I found was 1440 HDD - But I could be reading it wrong as I have only just looked it up!!

I found another chart that shows 3000 HDD from a base of 65 - I think I found 1440 on a different chart...


Thanks!

I would start with tightening the envelope up, a couple of inches of foam on the exterior of your 2x6's for a start and a bit more above.

Insulation is a one off payment, gas and electric are forever and will only increase.

With better insulation you might find in floor radiant overkill.

I just completed a 2500 (or so) sq. ft. house in Carmel, a few miles south of you. Here's some stuff that I can think of after my project:
- I used 2200 HDD as my baseline, with 68 as the base. Your HDDs would probably be about the same, or a bit lower. 1400 seems a bit low to me, but just a bit.
- I have a not particularly tight, 2x4, 2 story house with a fair # of windows *and* a 10x14 heated, standalone office. My heating load was about 40K at 30 degrees (38 degree differential, that is), or about 1K / degree / hour. I cannot imagine that yours will be higher, but you should know what it is. (And you will, for Title 24. Better now than later.)
- I installed a Munchkin 80K Contender boiler, which is plenty enough, as my load is not 40K, even on the coldest day. (I watch it. Trust me, I watch it.) I also have a hot tub that the boiler heats, as well as an indirect DHW tank. There's no conceivable way that 150K is the right boiler for you. Either your house is made of glass, or you have forgotten to put in insulation, which (given Title 24) seems unlikely.
- I think - in hindsight - that if I didn't have my solar panels, nor the hot tub, I might have been better off with a tank rather than the boiler. But, I had the tub, and the boiler is cool.
- I found - in my calculations - that 2x6 walls didn't make that much of a difference for me given my windows and my ceilings. There's no earthly way that you need foam outside of your 2x6 walls. No earthly way. 8" walls in Santa Cruz? Not a chance.
- Don't forget to find a good control system. I found Tekmar, which I'd heartily recommend, but it's not inexpensive.

Drop me a note if you'd like to come down.

Jeff

DegreeDays.net reports Monterey Airport as 3400 HDD at base 65/year, and usually we'd recommend doing base 70 for anyone who cares enough about their comfort to consider radiant.

Degrees days are really only useful in relative terms as Rob is using them here.

The use of degree-days as an equipment-sizing tool is obsolete as it was devised at a time when fuel was cheap and houses were poorly insulated. Since new homes are very well insulated by comparison many of the "degree days" will not put any load on the heating equipment. This is due to the relative output or internal gains of people, lighting, appliances and the like.

The net result of overusing degree-days data is to oversize heat source and emitters both driving up fuel usage and driving down comfort.

Naturally degree-day-calculations have no function in passive solar design loads.

About half of my work involves correcting poorly designed radiant heating systems most of which, start with WAG heat loads. The use of the free Slant-Fin software constitutes a reasonable but misleading attempt to improve the WAG but will not help with emitter sizing or design water temperatures so is really useless for radiant walls, floors, ceilings connected to condensing boilers or ground source heat pumps.

Every good radiant heating systems starts with a room-by-room heat load analysis, performed by an experienced designer, using software made for the purpose.

HDD aren't about equipment sizing. But they are useful in helping determine the CLASS of heat source to use. And in this area of the country, it's pretty hard to cost justify anything more robust than a decent tank water heater. Even at my higher HDD count!

But, most homes in this area probably would scoff at such concerns... having anything less than a mod/con would be embarrassing

I'm embarassed by my 2200 HDD number (where did that come from if not my addled brain?) but not at the boiler, which also does double duty as a hot tub heater.  Boilers are hot! 

Thanks for all of the responses - energy calcs have been run on the home, room by room, which I don't quite understand - certainly trying to learn more.

Initially I was looking at having a tankless NG heater like a Takagi or similar and then a downstream 5 gallon buffer tank to eliminate the hot sandwich, but was directed to a boiler by the designer as a better solution.

In our last house, a mile from the new house we are building, we had 2x6 walls, foam on the exterior under the siding, and super plain 1980's wood dual pane windows with removable interior panes. Our house had electric radiant heat in each room (ceiling panels in rooms, floor heat under bathroom tile), and a tankless Takagi water heater. With this house we never had electric/gas bills over $110 in the coldest months with 3 people and a baby...

I am hoping our new house, while certainly 2 times the size will have better efficiency based on modern windows and house sealing.

Posted By NRT.Rob on 01 Feb 2011 10:19 AM
having anything less than a mod/con would be embarrassing

Well, I for one don't plan on showing off my utility room!!! - SO I am looking for the best options for our home...

Pretty funny, but I can think of a few people who might though...

Thanks!!! - Do you recommend I go a certain direction?

well, if you do a good job on your system, I bet you will show off your mech room. Ask Jbaron about that

I recommend a heat load calculation and analysis. it will likely turn up that a good size tank water heater is the answer, separated with a heat exchanger (might need a dual wall unit by cali code, though)

Mechanical rooms - or in many cases, basements such as mine that are devoted entirely to infrastructure - are the newest trend in interior architectural design.  Colored concrete floors, spray painted pipe insulation, red, white, and blue appliances, and stainless steel and bamboo work tables and shelving - it's all good.  In fact, Martha Stewart (via Kmart) has just released a new line of mechanical room furniture - made entirely of sustainably produced concrete.  It's the bomb, baby! 

Well - I will have my metal working shop (far away from the utility room) for that...

I am asking for more detailed energy calcs, as the only ones I have right now are on the drawings for permit & plan approval than include the Title 24 California compliance.  These don't have BTU loss per hour or total heat load that I can see.

Is there anything I should ask for specifically from my designer?

While I wait for my more detailed energy calcs - here is another question:

Original spec is for a Lochinvar KBL150 - which may be just fine or it might be too big for the job...with better numbers I hope to have a clearer picture

I have also been told by a relative in the HVAC business that I should also look at Raypak or Laars as an alternative to the Lochinvar boiler.
Anyone have opinions one way or the other on any of the above???

you want room by room peak load calculations, and then you want a yearly energy analysis comparing mod/con with tank heater performance.

sounds like your relative works in the commercial realm. You should look at whatever boilers are provided and serviced locally.

While you are waiting on the designer for those room-by-room numbers, my Title 24 page included a section called "HVAC Sizings." The number that I had listed there (55K) was produced very early in the process of putting plans together, before drawings, etc., but it was only 15K too high. Most of the places that produce these reports put down "a high number that passes inspection" so as to not get caught by the numbers, so your number may also be high. But, you should have it on that page.

The eventual number of 40K was arrived at via the room-by-room analysis, and was surely more accurate.
 
Also, to speak to Rob's quote about getting something serviced locally: my plumber fell into a maintenance job servicing a Veismann boiler that "the fancy place" around Carmel loves to spec and install.  Great boilers - maybe - but when a circuit board went out, it took 3 days to troubleshoot a strainge boiler, and then get a part for it via FedEx overnight from Timbuktu.  Don't go down that route.  This is not rocket science.  Get something normal, except for the furniture.

Jeff

I just finished a design for a retrofit radiant system in Oakland, CA. They got a condensing water heater with single-wall heat exchanger following the ICC plumbing and mechanical codes.

Sweet. That double wall requirement was stupid.