\"Free\" enrgy for Snowmelt

ScottMP

Dale

I am certainly not in the same league as the minds that are discussing this post but may I say that some of the greatest achievments in mankind came from ideas that "Will never work " ! " Man will never walk on the moon "

In ME's Target store, what if the snowmelt was run by the Domestic water as a preheat to the heater during the summer time. Would'nt that be a simple way to save energy ?

An enginner friend of mine told me of his first job where he was watching as the company removed an old iron scafolding that was supporting a several thousand gallon tank. His new employer has designed a new light wieght geodesic support stand. He was very impressed. A little less so when the tank was lowered and crushed the new stand flat on the ground. No one is perfect and laws are made to be broken, sometimes.

Scott



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hr

Dreamers, rule breaker, pioneers..

I support folks of the mechanical bent that fall into this category

I have a shop full of Rubes! I know many of us do.

I would caution about selling customers "questionable" homemade technology.

Keep thinking outside of the box, boys and girls.

hot rod

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Dale Pickard

In ME's Target store, what if the snowmelt was run by the Domestic water as a preheat to the heater during the summer time. Would'nt that be a simple way to save energy ?

Sure, but just because you can do something doesn't mean that you should. I don't imagine Target stores have much of domestic water heating load. If you don't use much dhw than your investment in the conversion won't pay back very quickly because you don't offset much conventional energy use. If the conventional energy is cheap, like NG, then you don't save much $$ for the energy that you do offset.

Also, it's not such a simple thing, controls, heat exchangers, piping, etc.

All I'm saying is that there are ways to put a pencil to these things, and when you do, the results can be illuminating.

Dale

Ohhh, about your freind, sounds like he was a lousy engineer. There is a difference between engineers and engineering. Just because your freind interpreted the rules poorly doesn't change the rules.

Dale Pickard

That all makes sense

but I still say that the devil is in the details.

You said,

"If joe homeowner pays $100/mnth heating the home and $300/mnth melting the snow off the dirve I say heat as much of whichever load you can."

I think that these are broad assumptions that you are making.

All I am arguing for is that it is possible to be specific and calculate realistic answers to these questions rather than make broad and baseless assumptions that are chosen to support the case that we want to make.

Snowmelting represents a large episodic, heating load that always occurs during the worst times for a solar contribution. Snowmelting doesn't necessarily represent a large annual load, like space heating or certainly domestic hot water which is a year round load. I'm sure that it depends on the "climate".

One of the rules of solar applications is the the best ones, the most efficient and most cost effective are those in which the supply closely follows the load. The times of greatest supply, summer, is the time that you really want to have a load on the system, because then you are offsetting the most conventional fuel.

Another rule is that one should never fire an auxilliary heat source into the storage tank. It's an inefficiently way to fire the distribution system by the boiler, that has no need of the tank. More important, firing a boiler into the tank really screws up your solar system efficiency.

If the tank is already hot, it's difficult for solar to put more heat in it. The DT control will prevent the system from operating until the collectors are hotter than the tank. Operating the collectors at temps that are higher than necessary increases collector heat loss and decreases collection efficiency. If you fill up your storage tank with conventional heat, there is nowhere to put the solar heat.

Solar systems are quite expensive and need to represent most fuel offset possible. Many people can be pretty disappointed when the real economics are determined. It's not at all hard to achieve only 20-30 year paybacks.

The inverse of payback is return on investment. What we really want to do is put our several thousand dollars into something that grow faster than some other investment, like say a CD or a savings account.

Dale

ScottMP

He did

mention something about a photo lab.

My friend was a new employee who sat and watch the older smarter enginers. He was so impressed with the design, as he watched it disapper under the tank. Just a funny story, nothing else.

As I said some of the greatest inventions came from people who did'nt listen to the rules.

Scott

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Dale Pickard

Yes, I would caution that as well.

The solar industry has already seen enough compulsive engineering. It's hard to be a responsible designer and be lumped in with people who are uninformed and experiment on their customers.

I'm all for thinking outside the box, but I don't think that is what's being promulgated in this thread. I pick up on a lot of anti intellectualism, anti engineering.

Dale

Mad Dog

hee hee...nope there are still some psychos left out there

you are in good stead. Mad Dog

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David Woycio

IF

> but I still say that the devil is in the

> details.

>

> You said,

>

> "If joe homeowner pays

> $100/mnth heating the home and $300/mnth melting

The operative word is IF. The point that I was making is that saving energy is the name of the game. For example it does my clients no good to save energy in a large solar heating system for domestic hot water use (not letting the tank get below 120 deg.) IF the annual gas bill for the hot water heater is $150 and IF the home heating bill is $2000.
> I am arguing for is that it is possible to be

> specific and calculate realistic answers to these

> questions rather than make broad and baseless

> assumptions that are chosen to support the case

> that we want to make.

I would hope that anyone in this business would not start out designing a system without first performing a heat loss calculation and ,if designing the solar impact, a solar heating performance estimate.
> Snowmelting represents a

> large episodic, heating load that always occurs

> during the worst times for a solar contribution.

I concur that you cannot expect to melt snow off of a drive in ONE day of solar gain. But IF the excess heat from the system can keep the ground below the slab from freezing....go team! We are very upfront on the snowmelting capabilities (or in-) and the incredible draw on the solar system. But the costs in some instances on not so great to add the solar in the mix.
> Snowmelting doesn't necessarily represent a large

> annual load, like space heating or certainly

> domestic hot water which is a year round load.

> I'm sure that it depends on the "climate".

I would have to crunch the numbers but I would guess that 1-2 months of snow melting would equal the load presented by an entire year of domestic hot water use.
>

> One

>> Another

> rule is that one should never fire an auxilliary

> heat source into the storage tank. It's an

> inefficiently way to fire the distribution system

> by the boiler, that has no need of the tank. More

> important, firing a boiler into the tank really

> screws up your solar system efficiency.

Never mentioned heating the storage with the boiler. We see systems all the time that have been designed incorrectly (usually when the installer tried to heat the home using BB) where the boiler returns are plumbed to the solar storage tank. I was referring to systems where the homeowner uses a wood fireplace and we have installed a stainleess steel hx to capture excess heat to replenish the storage tank during times of no sun. We actually used to service systems set up like these but they had no back-up heat. The fireplace was the only back-up. Problem was you couldn't leave the house during the winter or face a possible major freeze-up. But fireplace hx work VERY well.
> systems are quite expensive and need to represent

> most fuel offset possible. Many people can be

> pretty disappointed when the real economics are

> determined. It's not at all hard to achieve only

> 20-30 year paybacks.

I agree that the systems can get pretty pricey. New construction or refinancing the current loan is an easier pill to swallow. We try to get the solar heating additional cost to equal the savings in utilities vrs. the additonal mortgaged amount. With the rise in utilites or clients who live in a higher utility rate area solar heating makes very good sense. Also for some people its not about the cost as much as what can they do to save eneergy. Insulation, resonsible building, energy efficiency, and solar heating all have a place. Also my company recycles solar collectors. We can sell collectors for a fraction of cost and if we install them provide the client with the same warranty as new. Some of the older collectors (such as Novan or Moriningstar) are still putting out about the same btu's as new. The great thing about flat plates is that since they are made of copper you can aways repair them with a little elbow grease and some brazing rod.
>

> The inverse of payback is

> return on investment. What we really want to do

> is put our several thousand dollars into

> something that grow faster than some other

> investment, like say a CD or a savings

> account.

If you really want to save money move back in with your parents or friends and turn the thermostat way up!