Adding Storage to EKO - Problems with Simplest System.

[Medman]

Well, I have hit a snag with my retrofit of my system to the simplest system design (see diagram below, but I have no oil boiler). The problem is that I have a 140' separation between the storage and boiler and my house loads. I have no signal communication between the two.

I am trying to avoid circulating water from the shop to the house when there is no call for heat.

I cannot use the storage aquastat to control the load circulator, since there is 140' between the two. I have been thinking of a system with a timer, as in
"turn on load circ when there is a demand for heat. Wait x seconds, if supply pipe is hot (from boiler or storage) then continue, if not, shut load circ off". After a certain amount of time, the thermostat will engage the backup elec. heating elements - this is already in place with my furnace.

Do you have a simple solution for this?
If I have to keep water circulating in the loop at all times, would it be better to plumb in the storage differently, so I am not heating the cold boiler?

Thanks for your help. I am stuck on this, and I don't want to buy pumps, etc. until I have a design that will work and be efficient.

Ryan

 

[stee6043]

What are your "loads"? Are they controlled by a thermostat? The way I accomplished basically what you are looking for (I think) is by using two circ pumps controlled sperately. My primary circ which is controlled by the boiler only pumps between the boiler and storage. I have a seperate pump on my load loop which, when on, circulates water from my storage/boiler to my load.

I control the second pump with a thermostat. This insures I'm never pumping hot water to my load when it's not needed. But the boiler primary circ can still run anytime the boiler is up to temp.

Did I completely miss what you're asking for? Wouldn't be the first time...ha.

 

[Nofossil]

Do I assume that the boiler and storage both are in the shop?

I think it would work OK if the load circ is in the house and is controlled by the thermostats so that it runs whenever there's a demand for heat. It doesn't matter what's happening in the shop.

At the same time, th boiler circ should run whenever the boiler is hot. It doesn't care whether the house needs heat or not.

The purpose of the storage aquastat is to disable the fossil boiler. Since you don't have one, you don't even need a storage aquastat. Your family will let you know when the top of storage has cooled to the point where it's no longer useful ;-)

 

[stee6043]

FYI - The parts to do what I mentioned above are super cheap if you already have the pump. Thermostat, relay, transformer...done. $50 maybe? Depends on how fancy you want the thermostat to be.

 

[Medman]

My loads are a sidearm hx for dhw and a water-air hx in the plenum. The furnace thermostat is a multi-stage unit that controls the plenum hx circulator, furnace fan speed, and backup elec. elements.
I have a boiler circ (labeled wood circ in the diagram) for the boiler and storage.
Really what I am trying to prevent is pumping cold water from storage through the plenum if both boiler and storage are cold. Since the main circ (load circ) may not have hot water present when it is energized, how can I prevent it from pumping cold water through the plenum hx? In the attached diagram, this is prevented by the contacts on the storage aquastat, but I have no way of connecting the two in my case.

 

[Medman]

I have everything needed (relays, transformer, snap-disc sensors, aquastat) to add the storage except the pump for the boiler loop. Right now I use one large circ and continuously circulate water whenever boiler is hot. (no storage). This large circ would become my load circ. and move to the house, close to the loads. Small pump would be used as the boiler circ.

Storage and boiler in shop, 140 feet from load.

Family is a good indicator of low temp, but I am trying to prevent cooling the house off/using elec. heat backup to heat water in the loop when I am not home to tend the fire!

 

[stee6043]

How about using an aquastat and a thermostat on your HX loop circ pump circuit? Use a make-on-rise aquastat mounted on your boiler. Run your circ pump from this circuit. Use your thermostat to control the pump. With this setup if your boiler/storage is cold but you have a call for heat the aquastat will be open and thus the pump won't run. Conversely, if your boiler is hot the aquastat will be closed. If you get a call for heat the thermostat will be able to turn the pump on.

 

[Nofossil]

I'll echo the last post, but perhaps the aquastat should be on the pipe right at the top of storage. If the boiler or storage is hot, the aquastat will be closed and allow the load circ to run.

Really, it's not the end of the world if the load circ runs when the boiler and storage are cold. They'll never be cold enough so that you're cooling the house.

 

[Medman]

Again, thanks, but the aquastat would be at the storage end and the circ would be at the house end - 140' away - the start of this problem.

NoFo, I think you make an excellent point, that I have overlooked. Water circulating even at 70* F will not cool the house! I think that I will install a lower-limit cutoff on the inlet pipe at the house. I have some 60*F sensors that will not allow the circ to run once temp coming into the house from storage or boiler drops to 60*. I use this same sensor to control the elec. backup elements - they will not energize until the plenum hx temp drops below 60*. This ensures that the only time the elements are used is when I am away for extended periods.

As usual, a simple solution. Thanks, and I will let you know how this plays out.

 

[Nofossil]

Again, thanks, but the aquastat would be at the storage end and the circ would be at the house end - 140' away - the start of this problem.

NoFo, I think you make an excellent point, that I have overlooked. Water circulating even at 70* F will not cool the house! I think that I will install a lower-limit cutoff on the inlet pipe at the house. I have some 60*F sensors that will not allow the circ to run once temp coming into the house from storage or boiler drops to 60*. I use this same sensor to control the elec. backup elements - they will not energize until the plenum hx temp drops below 60*. This ensures that the only time the elements are used is when I am away for extended periods.

As usual, a simple solution. Thanks, and I will let you know how this plays out.

Just a random question: How hard would it be to bury some 3/4" black plastic pipe between the buildings? It only needs to be a few inches below the surface, and you could run any low voltage that you need through it - sensors, Ethernet, phone, relay control, whatever.

 

[Medman]

I have considered it, but it would be difficult at this point. Pipe is buried 6 feet down under the driveway, which I had levelled and new stone spread this summer. Digging this up now would be a challeng to keep neat and look good after, and my wife already thinks I`m crazy - if I dig again I will be divorced for sure!

Another option I have is overhead, as I have phone line that runs from pole near shop to the house. I would have to run appropriate cable from shop to pole, then to house. It`s an option but a last resort in this case.

I am going to try the sensors for now and see how it goes. If it doesn`t work as planned then the cable is the next option.

 

[markpee]

The purpose of the storage aquastat is to disable the fossil boiler. Since you don't have one, you don't even need a storage aquastat. Your family will let you know when the top of storage has cooled to the point where it's no longer useful ;-)

NF -

I'm going to be adding storage soon, and am wondering how the aquastat on the storage works - does it shut my oil boiler off when the tank is above a certain temp? Do you have more info on this?

 

[sdrobertson]

Digging this up now would be a challeng to keep neat and look good after, and my wife already thinks I`m crazy - if I dig again I will be divorced for sure!

I know what your talking about...bought my house in 2000...put in my first homemade OWB, it rotted out and put in a Central Boiler in 2005. Took it out in 2008 and built a polebuilding and went with a gasifier. Kinda hard to explain the savings up to this point.....

 

[Nofossil]

NF -

I'm going to be adding storage soon, and am wondering how the aquastat on the storage works - does it shut my oil boiler off when the tank is above a certain temp? Do you have more info on this?

There are endless possibilities for this. The approach suggested in 'simplest storage' is to use a break-on-rise aquastat and wire it in series with the 'demand' signal that goes to the fossil boiler. That way, the fossil boiler never sees demand if storage is hot.

The demand signal is typically a low voltage switch closure. It could be thermostat contacts, or zone valve limit switches, or relay contacts in a zone control box. Makes no difference - interrupt that circuit and the boiler doesn't go on.

 

[stee6043]

I have considered it, but it would be difficult at this point. Pipe is buried 6 feet down under the driveway, which I had levelled and new stone spread this summer. Digging this up now would be a challeng to keep neat and look good after, and my wife already thinks I`m crazy - if I dig again I will be divorced for sure!

Another option I have is overhead, as I have phone line that runs from pole near shop to the house. I would have to run appropriate cable from shop to pole, then to house. It`s an option but a last resort in this case.

I am going to try the sensors for now and see how it goes. If it doesn`t work as planned then the cable is the next option.

I have to believe you could find a readily available wireless option. I just wonder what the cost would be. The easiest would be using wireless ethernet and a PC in the house. The trick is you'd have to have a board in your PC to make the switch. And that might be more expensive than burying all new pipe....not sure though.

 

[mwk1000]

I was thinking the same -- RF is one way to keep the yard intact. Starts to loose the "simple" aspect though! I am dying to try out one of these http://arduino.cc/en/Main/ArduinoBoardDuemilanove. It is the simples cheapest way I have seen to getting into the controlling game and having a lot of options. Using an old throw away PC with Linux ( Free and Free ) USB so no mucking about inside the PC. You set it up set the logic it runs independent of the PC. But again - not quite adding an aqua-stat is it? But fun. This might be right up NoFossils alley.

Mark Kirkpatrick

 

[Nofossil]

I've done lots of work with Arduino-style boards. It's a very cool piece of hardware at a really low cost. It doesn't have the horsepower for what I want to do, but it's a great solution for those who like that kind of tinkering (like me). I may end up getting one to play with and set up as a remote slave for my NFCS.