Design questions: Boiler outside and elevated above basement storage tanks?

[Beerdog]

I'm looking for your thoughts about how to design a pressurized system with the tanks located in the basement and the boiler about 5' above in an out building at grade level.

I'm still struggling with the concepts and price of a boiler for a new house and am in the design phase; I don't have a place for a wood boiler in the house. The house will be tight and very well insulated. I estimate the heating load at about 25-30k Btu on an 80 degree differential. To satisfy the bank, I'll need a propane, oil or electric heating system and will likely use propane with a mod-con boiler and baseboard. I also want to include a wood boiler because I have wood. Because the house is tight, the anticipated heating costs will be low, so fuel savings will be small and payback will likely be many (20) years, so using a wood boiler is not just an economic decision, but a decision to wean my home off fossil fuels.

I'm considering placing the boiler in an outbuilding and the storage tanks in the home's basement. What are the pitfalls and design considerations? How do I protect the boiler from draining into the storage tanks as the cooling water contracts? Can I use antifreeze to protect the boiler from freezing? Do I need an expansion tank elevated above the boiler to ensure the boiler retains water in is jacket? I assume that I'll need a boiler loop filled with antifreeze and a loop for the storage water (2 circulators) and just to heat the storage water. Am I on the right track?

I'd love to place the boiler in the basement but the dust & wood mess, smoke, combustion air and flue all present problems in a tight home.

Thanks for your thoughts....

John

 

[jebatty]

Hot water baseboard is not the way I would plan to heat a new house. I would plan for either/both in-floor radiant or low temperature radiant panels. With a wood boiler system you want to be able to heat the house with as low temperature water as possible. The higher the temperature of needed water, the less flexibility and efficiency you will achieve with a wood boiler. Low temperature radiant often can meet needs with supply water as low as about 100F; baseboard may need water up to about 180F depending on design.

With a pressurized system there should be no problem with the design concept you are considering. If freezing is a concern because you will be shutting down the wood system from time to time, then you likely will want to isolate the wood system (but not the storage) from your main heating system. This normally would be done through a plate heat exchanger or a coil heat exchanger in your storage tank. The heat exchanger effectively is the "load" the wood system will supply, so all plumbing is designed as such: size of piping and circulator to carry needed btu's, expansion tank, air scoop, etc. This system will not have much water in it, so antifreeze would be a reasonable way to plan. The system will never "drain" into the storage tank because the system is pressurized; it will always be full of liquid at about 12 psi minimum at the boiler.

Your house system, including storage, will need sufficient expansion tank sizing based on the added liquid volume in your system.

 

[Fred61]

One way to reduce your payback period would be to scratch the mod con if it is only going to be used for back-up.
Listen to Jebatty on the heat distribution. You'll never regret installing radiant.

 

[Beerdog]

Jim...

Thanks for your reply. You're confirming the approach I was considering. My concern with radiant is response time. I've heard concerns that the radiant in floor is slow to respond, and about half the home will have carpet. I'm looking into radiant panels... I haven't seen them used in residential use. House is being built as a modular and so hydronic radiant in the walls or ceiling is not going to happen. I'm looking into low temperature baseboard to see what's available, and I can do radiant in the floor as a nail-up.

Around here radiant is thought to be the Cadillac heating system and installers charge as such. To keep the costs down I may have to install myself as retrofit. Thanks for your suggestions. In particular I hadn't thought of the heat exchanger as being the boiler's load.

Been thinking of a well insulated Garn Barn with some supplemental heating in case I should decide to abandon NY for a month in January. Since I need storage and a boiler, that may be the simplest solution.

John

 

[flyingcow]

I have base board throughout my house, with staple up in my kitchen. I installed the staple up myself, and had a heating contractor hook it into the system. Works well. I will say with BB t is nice for quick heat. The staple up will be nice DIY project for the future. Once you get the radiant installed and working, it will work excellent with a tight house.

Also, my boiler is not in the house. For me, I like the set up. Big bonus is that I stack my wood on pallets(avatar) and move around with my tractor.

 

[PassionForFire&Water]

Radiant floor heating, desingned properly will have no issues at all.
It also will save you money over time because you can keep the temperature down 2 or 3F

TIPS for a new construction:
- insulated insulate, insulate.
- make it tight, tight, tight.
- Provide for proper ventilation.
- Take advantage of passive solar
After all this, you probably don't need much a wood boiler at all.

You are in the best position to do it right and safe big $$$ for the rest of the years to come.
Remember, energy cost will only go up.
Any $$$ spent on insualtion today will have a big payoff for the years to come

Study "Passive House" (this is different from passive solar): (broken link removed)

3,000 to 6,000 BTU/hr heat load is within reach these days without spending much more then a conventional construction.
Probably finding an architect/designer that knows what he is doing will be your biggest task.

 

[jebatty]

I've heard concerns that the radiant in floor is slow to respond.

This probably is true if tubing in a concrete floor. Others will have to respond about staple up response time. But in general, low temperature radiant is designed to be "on" most of the time, but at a temperature to maintain the house at the desired "feel" or room temperature. Non-radiant systems supply a blast of hot air to warm the house, then shut off, and cycle on and off. Radiant is more or less a constant low temperature heat, usually very even, not drafty, and no temperature swings. Outdoor re-set thermostats and control systems can adjust a radiant system supply temperature automatically based on outside temperature to minimize any perceived delay in response time and maintain the desired inside temperature.

I suggest you do a lot more research on radiant systems. If I ever built a new house, radiant is the only way I would go, and then only low-temperature radiant panels. The first time I saw this was back in the early 1980's at my cousin's house in Germany which had very attractive panels which blended in well with room decor. Incidentally, my cousin's house also had windows which put to shame the quality of windows in the US, low flow toilets and faucets which barely used any water but were fully adequate to meet needs, and in general a very "green" house at a time when being "green" was mocked by many in the US, and still mocked by some yet today. I think my cousin laughed all the way to bank, and still is laughing 30 years later. Energy conservation pays well. An investment now will pay back the entire lifetime of the structure while energy prices continue to rise.

 

[Downeast Farmer]

Just curious, Jim: by low-temperature radiant panels, do you mean those nifty European flat-panel radiators, or a radiant floor panel? If the former, why not the latter?

 

[flyingcow]

I'm with jebatty- if i was to rebuild one of my first choices would be radiant with an outdoor reset. Or rebuild in a warmer climate.

 

[Downeast Farmer]

Same question to you, flyingcow, radiant panel radiators or radiant floor? Any reason to prefer one over the other to you?

 

[flyingcow]

For me, it's flip of the coin. But I like the looks of the rad panels, but it's some nice having the tile floor in the kitchen warm. Makes my wife happy......................and well......thats all that matters.

 

[Fred61]

If I were building new right now, there would be no need for a wood boiler. Engineering and proper insulation would satisfy most of my heating needs. Investment in a wood boiler would take much more than 20 years to pay back.

 

[Bob Rohr]

For me, it's flip of the coin. But I like the looks of the rad panels, but it's some nice having the tile floor in the kitchen warm. Makes my wife happy......................and well......thats all that matters.

It is easy to blend radiant floor heat and radiant panels. Use radiant floor heat inn the bathrooms, maybe the kitchen area, or any hard surface where folks stand around.

Panel rads are ideal in bedrooms and the remaining rooms as they ramp up and down quickly and can be zoned easily. There are tons of color, shape and sizes available in panel rads. It's fairly easy to build radiators also. Copper tube, steel, even concrete can be molded into radiators.

 

[PassionForFire&Water]

It is easy to blend radiant floor heat and radiant panels. Use radiant floor heat inn the bathrooms, maybe the kitchen area, or any hard surface where folks stand around.

Panel rads are ideal in bedrooms and the remaining rooms as they ramp up and down quickly and can be zoned easily. There are tons of color, shape and sizes available in panel rads. It's fairly easy to build radiators also. Copper tube, steel, even concrete can be molded into radiators.

Hey Bob,
Now you made me curious.
Concrete radiators????

Any website or links?

Thanks!

 

[Beerdog]

Thanks all for your thoughts. With my open floor plan, wall space is at a premium and so I'm looking at the 6" high radiant panels baseboard units apparently made by Hydronic Alternatives out of Springfield, MA. They're not far from me. Looks like they deliver about 100 Btu/linear foot so I'd need about 250 linear feet. That will be tough so I'm thinking of stacking them one over the other to give me a 12" high baseboard. I'll have to see if this is possible.

Warmboard sheeting under the floor is another option, but cost is a concern here. When it came out it wasn't widely distributed here on the east coast and it's a premium product. From the standpoint of installing it, it's not a problem for a construction crew that uses it regularly, but in a factory setting where it's not been used before it could cause problems with schedules, timing and work habits, and it would have a learning curve. I can speak with the modular manufacturer for an opinion. Staple up looks like a better alternative at this point. Radiant panels in the walls are also problematic.... someone will want to hang a picture or mount something to the wall, so future wall use needs to be considered.

I haven't found much else yet on radiant panels... still searching.

John

 

[jebatty]

they deliver about 100 Btu/linear foot so I'd need about 250 linear feet.

At what water supply temperature? And at what gpm flow rate?

 

[Beerdog]

Jim...

From Table A at (broken link removed to http://www.hydronicalternatives.com/getattachment/c19becec-22c5-46bb-aeae-355c18e424f4/RadiantPanel-Installation-Guide.aspx) the flow rate is 0.07 gpm, and Btu = 104 @ 140F, down to 72 Btu @ 120F

John

 

[jebatty]

Looks pretty good. You will have to zone/plumb to maintain temp/flow. Based on these numbers, you also can determine how much different quantities of storage will provide you with hot water between boiler firings. Good luck on this. Keep the thinking going and work out a very good plan and you will not be disappointed.

 

[ihookem]

Just an observation about stapling up pex under the floor. I hooked 250' up under my family room. There is padding and thick carpet above it but still works very well. If I have the house @ 66 degrees it is comfortable. I can take a thermometer , put it on the floor and cover it with a towel the thermometer reads about 90 degrees. It makes better and more efficient heat. I want to do more of the house cause it's so much quieter than running the forced air. Forced air is loud , not very warm and creates a draft. Pex is cheap too. 100 bucks for 250 ' makes one zone, plus r11 insulation is 80 bucks?. I made my own aluminum staple up heat deflectors so that was all but free.

 

[ktm010]

Just an observation about stapling up pex under the floor. I hooked 250' up under my family room. There is padding and thick carpet above it but still works very well. If I have the house @ 66 degrees it is comfortable. I can take a thermometer , put it on the floor and cover it with a towel the thermometer reads about 90 degrees. It makes better and more efficient heat. I want to do more of the house cause it's so much quieter than running the forced air. Forced air is loud , not very warm and creates a draft. Pex is cheap too. 100 bucks for 250 ' makes one zone, plus r11 insulation is 80 bucks?. I made my own aluminum staple up heat deflectors so that was all but free.

I installed this type 22 yrs ago when I built our home, just looked the spec up 220 BTU/HR at 180* at 1 gal/min

 

[Bob Rohr]

Hey Bob,
Now you made me curious.
Concrete radiators????

Any website or links?

Thanks!

Here are some ideas for concrete radiators. The concrete counter top is in my bathroom, very easy to build. I believe Sackrete offers counter top mix now. Just loop some small diameter pex inside. The dog was cast at a local concrete shop, I had them install stainless CSST tube inside. My mother in law painted it for me. Weighs about 400 lbs! I also built a heated Venus statue for a friend.

Jaga and a few others offer concrete radiators ready to go.

 

[Beerdog]

Bob...
The dog is one of the most creative uses of functional design I've seen. Creative genius!

For what it's worth, for the time being, I'm holding off on my plans to install a wood boiler until I see how things work out. Since I've decided to be as efficient as I can with my heating fuel source, and since I have to have an electric or fossil fuel energy source to satisfy the bank on my home project, I've decided to use a mod-con propane fired boiler. Though propane is expensive, the installation will be a lot less than the cost of a groundwater based heat pump to install (even with the 30% tax incentives).

The good news here is that efficiency with a mod-con boiler forces me to use a low water temperature radiator and so I've decided to forgo the builder's inexpensive baseboard and use staple-up radiant tube under the floor. This puts me in great shape to use a wood boiler down the road. Staging it over time will allow me to see how things go, to figure out how best to fit a wood based fuel system into my lifestyle and a chance to slowly plan it into the overall site design.

Unfortunately, solar is not an option. The site's a north facing slope and I was there in late December at about noon and the sun never rose above the tree tops. But I look on the bright side.... The non-native Asian longhorn beetle and emerald ash borer will hit my hardwoods at about the same time I'm ready to move on to a wood boiler. The trees will die, I'll have sun and 20 acres of standing dead wood to cut and burn. When I run out of wood I can put up a solar system. The deer, bear, moose, skunks, porcupines, bobcat, chipmunks, salamanders, frogs and birds will just have to find some other places to live. But at least I'll be warm.

John

 

[heaterman]

It's usually wise to ignore your builders advice on heating systems. 00% of the time they only think about lowest first cost rather than over the life of the structure. Discussion of comfort levels for radiant vs forced air will make their eyes glaze over........

Marc's advice is spot on. Insulate Insulate Insulate and make it tight. Using a heat recovery ventilator does wonders for the "feel" of a super tight house and you can make them double as bathroom exhaust also.

Use the lowest temp "emitter" that is practical for your budget and you'll probably find that payback on a wood boiler is far far down the road. If I was in your shoes I would sure think about either a small pellet boiler or else a standard type wood stove to take the "edge" off in the coldest months.

 

[Beerdog]

Heaterman...

Insulation and building tight is the approach we're taking. The house will have a 30,000 Btu heat load at a design temp of 80 degree differential. It's modular construction and nothing really exotic.... paying attention to air sealing and use of extra thick walls. But downside to having a tighter house is that it becomes less and less cost effective to use a boiler for space heating, and thought the boiler can be downsized, many of the parts are more expensive, so the overall system is more costly than a bigger, more inefficient system.

The wood boiler prices ranged from $7-11k for the boiler, $3-10k for storage (just for parts/components), and then I needed to add labor, parts and materials and design expertise to put it together. I was figuring the cheapest system I could build would be about $14k if I built it myself out of scavenged components. It would take a long time to recover the costs if my heating bills are only about $1-2k/year.

We decided to install a wood stove in the basement (my space) and an efficient zero clearance fireplace for heat and ambiance on the main level. The costs will be less than a boiler and the units will serve as a backup for when the power goes out.

If the costs for propane get out of line, I'll reconsider a wood boiler and because of the installed hydronic radiant, I'll be in a good position to install a unit sized for my needs.

John

 

[maple1]

My boiler was $5500 and storage tanks were $800 (including one for expansion).

Fully functional in a power outage.

There are also boilers out there less expensive than mine.

That is to say, YMMV and everyone should indeed fully evaluate their own situation.