Solar Pre-heated Water - Need Help Getting Water To Flow

it's not clear from your description.
1.The water supply for you hot water feed comes from the high level tank yes?
2. Is this tank open to the atmosphere or is it a closed tank under pressure?
If it's an open tank just feed to via a pump and a float switch to keep the header tank topped up.

If it's a sealed system under pressure then add a pump with a pressure regulator and a pressure swithc which cuts out the pump when the desired pressure is reached.
You don't want a pump running non stop into a closed tank doing it's darndest to rupture it.

I'm a great believer in gravity fed sytems myself, pretty reliable stuff gravity.
Del

The other point of course is that water can't flow in unless there is water (or air) flowing out.
I just refilled my hot water cylinder, even with a couple of hot taps left full on it took about half an hour for the water to start flowing.
Del

It's unclear what you are exactly doing. Is this for domestic hot water or a heating system? If it's domestic hot water then a faucet needs to be opened to get it to flow. If you have tried that and you do not get flow then you may have a valve closed or a plugged line. Maybe the original feed from the well pump still installed which would allow flow from there. How about posting a diagram of the system?

If it's for house hold heating then you need a recirculation pump.

Oh if these tanks are bulging are the designed for this application to hold pressure if not replace them with proper tanks before one ruptures.

Hi ozzb, Thanks for the response. I responded to Del with more info and a link to see a picture of the plumbing set up between the tanks. This system is for domestic hot water. We had the faucets open and the water would gravity feed but not come out under pressure to the hot water heater in order to feed the faucets in the house. We don't believe we have a valve closed or plugged line. If more info is needed I can try to diagram the entire system and post that.

What were these tanks originally designed for? They look like plastic fuel tanks. Which may have flow restrictor. When you attached the adapter to the tanks did you check to see if the inside was ported through. Or was it reduced. The vent screws when you vented the tank how did the water come out a steady stream squirting out or just slow. At 40 psi from the well pump should have squirted out such a small opening. If it didn't you have a problem with the feed from the well pump tank. Valve open all the way there? Unless there is some internal leveling valve in the tanks then the system would be under pressure not gravity feed to hot water tank. If there is internal leveling valves then the vent should be open. Gravity feed system would not be optimal if all the faucets are are at the same level as the tanks. No head pressure for flow.

I don't like the idea of theose plastic tanks bulging. I would check their pressure rating and buy some replacements that can stand it, if I were you, before there's a leak.

The rest of it sounds as though it's a plumbing problem. Did you install it yourself or did someone else put it in? Did it work and now it doesn't? What's going on?

Hi Bat, The tanks are water holding tanks used in sport fishing boats - we got them for free and want to be able to use them. In the boats they are confined with strapping on all sides that keep them in place. We may need to confine them also to keep them from bulging. We did the plumbing ourselves as we have with the whole house. Everything else works fine - just need to figure out how to get the water out of these tanks under pressure to the hot water tank. Right now it will flow by gravity to the hot water tank but the water feed into the 2 holding tanks won't stop when the tanks are full and it won't push the water out of the tanks under pressure. Right now we are not using the system so leaking isn't an issue but we would like to be able to hook it up to work.

Holding tanks are NOT designed to withstand 40 PSI!!! Sitting in the sun they will eventually leak and with 40PIS it will not be a slow leek!!! DO NOT USE THESE TANKS AS YOU ARE USING THEM NOW!!! As Horrible Old Bat suggested.

As Ozzb suggested you have a restriction in your flow path. It may be into the tank, inside the tank or between the tank and hot water heater.

Warning #2. Your picture shows a valve on the inlet side of the tank on the left but not the right hand tank. Then you have a valve on the outlet of the right hand tank.

If you close the top valve does it shut off all flow? It does not look like it will. Not if but when those tanks start to leak you will have to shut off the water closer to the well.

Try shutting the top valve and see if the situation changes at all. Then tun off the bottom valve. Does the flow stop completely? If not are you prepared for significant water damage?

The well holding tank is in the basement.

Is this a pressure tank?

If so, gravity is not going to work.

Right now you are using your greenhouse holding tanks as pressure tanks. That's not going to work either. Eventually, as they bulge and contract, they are going to rupture...............probably along a seam.

If you currently have a pressure tank in the basement like the one above, I'm having serious doubts about whether you are going to get much more preheating from an outdoor greenhouse tank, in the winter in Maine................it's cold out there!!!

If the greenhouse does get substantially warmer than your basement in the winter, forget the storage tanks, and just move your basement pressure tank to the greenhouse, or install a second one out there. You could even bump your pressure up to 60-70 PSI.

If you don't have a pressure tank, you should get one. You are seriously overworking your well pump without one.

Either way, the plastic holding tanks are out.....................they aren't designed to be pressurized.

Hi kramarat- thanks for the response. Yes we have a pressurized tank for well water in the basement. We are piping water from that tank upstairs to an attached sunroom that is open to the house with central heating and a woodstove. Solar heat alone keeps the room much warmer than the basement. Even with this information are you advising that the plastic holding tanks should not be used at all because they can't be pressurized?

You haven't stated the pressure rating of those palstic tanks, have you? It really pays to keep yourself well away from pregnant tanks.

Yes. You said they were holding tanks on a boat. Probably for live bait or something that didn't require them to be pressurized.

I know you want to use them, but by the time you install a secondary pump upstream to bring the water back up to household pressure, your going to be killing any savings you'd be getting by pre warming the water.

I'm sure you can find another use for them. I think your easiest, cheapest solution here, is to go to Home Depot, get another pressure tank, maybe smaller than the one in the basement, park it near the woodstove, (not too close), and call it a day.

Since you will be preheating the water in the sun room, it may be a good idea to wrap the pressure tank in the basement with insulation, keeping it fairly warm before it reaches the water heater.

So essentially what you would have, is a pressure tank in the sunroom, feeding the pressure tank in the basement, which would feed the water heater. Everything humming along at normal household pressure...............no worries.

Or you could eliminate the tanks from the sun room altogether and go with something like this.

It seems odd to me to have sealed tanks filling at the top and the water coming out of the bottom. That is just asking for airlocks. (maybe one of those holes near the top could have a blld valve fitted?)
I think you are possibly trying to solve too many problems at once.
1. Tanks bulgeing.
Answer:- Fit a pressure regulator onto the input side adjusted to a pressure suitable for the tank rating. Or fit higher pressure rated tanks.
2. Water not flowing out to water heater.
Water is flowing out to taps (faucets) (from the same tank yes ?) therefore the problem is in the heater, it's position (e.g is it too high above the tanks) or is down stream of the heater.
What is the output of the heater, e.g where does the water go? Are you letting water/air out? Is there any bleed valve or tap or you can open to check for flow?
Failing that, is there a compression joint just before the heater, you can slacken that off and see if there is flow.
If you don't let water/air out then none can flow in.
Once you have got water on the inlet side of the heater you can proceed to check to outlet side. Proceed slowly logically and with patience.

Long time ago I had an airlock in a downstairs radiator, it wouldn't bleed, it just sat there. In the end I undid the compression joint on the feed side and it didn't even weep... I pulled the pipe right out...nothing...I could see thesurface of the water about an inch down the pipe...I put my mouth over the end and blew, I could see then see the surface of the water moving slowly up and down a little. I then blew hard as I could and I heard a distant rumbling.I took my mouth off quick, just before the jet of water hit the ceiling. I got that pipe back on pretty damn quick!
Del

Kram is correct. If you don't have a "pressure tank" located in the basement you should install one along with a pressure switch to turn the well pump on and off. BTW, the pressure tank is also known as a hydropneumatic tank. When properly installed, it will pressurize your entire water plumbing throughout the house.

Ditch the "gravity" tanks and it's feed system, as it'll be a constant source of aggravation and will plain not work. Trust me on this one. I've seen a quite a few cob jobs like yours over the years as a consulting engineer and none of them ever worked properly for any length of time......ever.

Here's brief overview how the hydropneumatic tank system works:

http://www.ehow.com/how-does_5041211_hydropneumatic-water-tank-work.html

I highly recommend this hydropneumatic tank, as manufactured by AMTROL, an industry leader of water supply products. No, I don't have any interest in Amtrol, just a lot of successful residential and commercial installations over the years.

Nearly any well pump supplier and plumber can help you properly size the tank as well as install it (or you can do it yourself if you're handy at plumbing installations...).

http://www.amtrol.com/wellxtrol.html

PS: If you install a new hydropneumatic tank you'll also need a dedicated air compressor for the well pump and tank to operate efficiently and effectively.

Not the tank I have. Mine looks like the tank in the picture above. I used a compressor for the initial pressurization when I installed it 5 years ago and that's it. I forgot the PSI setting, but it's relative to the incoming water pressure.

It's been trouble free ever since. No dedicated compressor needed. I could have done it with a bicycle pump.

You still make some contradictory statements.
The tanks are above the heater and you say it's gravity fed.
But if the tanks are not open to the atmosphere then it is not a gravity feed it is reliant on the pressure of the incomming water.
Anyhow, open taps/joints/ drain cocks etc checking for pressure along the line. If there aren't appropriate taps/joints/draincocks then fit 'em!

If you want to make it gravity feed then the highest tank in the house needs to be an open (vented) tank fed via a ballcock.

The advantage of these is there is no need for electricity. the downside is the rubber seal/washer needs replacement ocasionally and you need to provide an overflow in case of failure.
Del

If the greenhouse does get substantially warmer than your basement in the winter

So many things that are easier if I had a minute and could gin up a drawing:

but I do understand the desire to make do and reuse

Presuming the statement above is correct and this entire assembly isn't going to freeze in the winter, AND presuming you are going to achieve some gain by circulating the water under the floor (which is exactly backwards to how greenhouses were designed in which you take hot water to plumbing under the floor to warm the greenhouse) the problem is simple: you have broken the pressure path and have to restore it downstream of your holding tanks since they won't take the pressure very long.

So you need a system from the basement that fills your tanks like your toilet tank, when full it shuts off the water flow BEFORE the greenhouse tanks pressurize. The tanks need to be around outside air pressure, so feel free to vent them.

Now you need a circuit to pass the water under the floor and back to the greenhouse tanks, this should dump back into the tank warmer, but again not pressurizing the tank. There are some very nice DC circulating pumps designed to run on solar panel output, see the logic - sun on greenhouse runs pumps only when the greenhouse is 'warm'. Until you can afford the PV panels you can run it off house current down converted to DC.

Now you need a circuit from your holding tanks to pressurize the house taps first passing through the regular water heater. Nothing special here, your plumbing supply can hook you right up with an on-demand pump that works like your well pump and shuts off when you hit target pressure.

So you turn on the shower, the household pump kicks on and takes water from the holding tanks through the heater to the shower.

The holding tank refills as needed from the basement.

The holding tank water constantly recirculates around the floor independent of the previous.

And don't ever let an inspector see this thing. He will not like you circulating drinking water under the slab, due to undetected contamination possibilities over the next umpty years.

I think both you and Del made some very good points. If the hot water tank is at atmospheric pressure it can not feed uphill to the other floors. Some sort of pump is required to maintain a system pressure since the warming tanks should be kept at atmospheric pressure and act as a holding or storage tank. As Del pointed out you shouldn't overfill the tanks and a float valve would cut the flow into the tanks. Those tanks are rectangular in design and the surface areas subject to pressure could blow them easily even at only 40 psi. It's no wonder they're bulging. You could install an automatic vent like on a hot water-hydronic system or on a radiator to vent off the air to prevent airlock. Probably could run a vent up and outside if a circulating pump is put in instead to prevent possibility of an accident inside.

I'm assuming that the water pump into the cold water tank has it's own cut-out so as not to over-pressure the float arrangement. Removing the tanks and installing copper tubing might be a very good alternate as someone mentioned. Then the need for an additional pump, float switch etc. would be eliminated since the well pump would maintain system pressure as it did before he added the tanks. Probably would still need a high point automatic vent to prevent airlock.

I'd take the tanks out of the system and replace them with a 300 foot coil (or 2) of 3/4" black poly line. It can take whatever pressure you're putting into it and has a lot more surface area for heat exchange in your sun room.

You'll derive very little heating from those tanks, since the plastic doesn't conduct heat very well, and the mass to area ratio of the blobs of water in them is high. You need AREA to heat water. Those tanks are NOT built for water system pressure. They're pumped with sucky pumps from the bottom, usually for deck and fish gut washing. I hope you're aware they might have been used for salt water, or anything, before you got them. And you can't drain from them if you close the vents with the pump off, and you can't pump with the vents closed or the tanks will blow up. High pressure 50psi or so tanks are made of steel, because that's 7200 lbs per square foot. 3.5 TONS. You're draining to the hot water heater from the BOTTOM of the tanks? And every part of the piping goes downhill? how high is the top of the water heater to the shower head?

Heating coils are in the floor, tanks are storage

There are no heating coils in the floor the cold water just flows through the tanks and was hoped to be preheated a bit before it was pumped through the electric hot water heater so the heater worked less , I am a friend of theres and know the scoop. Thank you Brian

GA to comments 20 & 21. These tanks are not really required, it is like a huge obstacle on the route. If heaters are gravity fed then the tanks should be kept open to atomosphre on top and higher size opening (1 1/2") should be used as outlet. Why tank should be allowed to bulge with pressure? As discussed in previous comments, these tanks are not efficient for absorbing enough heat for preheating. The best way out is to do away with these tanks as soon as possible. Install a metal tube coil in sun room (longer the better) and connect directly with heater. Copper tube would be the best, but any metal tube is OK.

i looked at your diagram looks ok but you said pipe from sun room tanks are taped into the pipe going to the hot water tank. if this is true you have set up a dead head if your tanks swell at 40psi when cold they will swell more if hot. to fix your problem you have to connect the pipe from the sun room directly to the cold inlet of the hot water heater and cap existing cold water pipe to water heater.

We want to thank all of you for your help on this issue. We certainly are not professionals but we did build the whole house ourselves - much of it out of recycled materials. These tanks were going to be thrown away - unused and we thought we could put them to better use than sitting in a land fill. Here is the diagram as best as I can do. We would still like to try and make this work somehow but if we can't we will just use the tanks to hold water and help to warm the sunroom.

like i stated in my last reply this new diagram shows two connections at the water heater one coming from pre heaters in sun room and also a cold inlet from the well also this is a dead head a valve will work as a cap as mentioned in last reply in the well supply line and a valve in the sun room line you will be able to use your water heater stand alone or in conjunction with you sun room system. to make it work shut the valve from the well to the water heater and open the valve from the sun room if its not set up like this the sun room tanks act as storage tanks with no through flow

The sense you employed to build a sunroom etc. should equally be applied to transport the product to destination. You probably know what to do, otherwise leave the transient tank at one atmosphere and employ a pump on its supply (discharge end) to get the water to its destination. I believe you insulated the dispensind reservoir?

I worked on a house in Paso Robles 20 years ago, that was designed with a TromWall(sp?)--55 gal drums behind a glass wall, filled with water, that keep the entire house within 8 degrees, plus and minus. If I remember, a 12 volt system was in place to "jumpstart the system, but it re-circulated on it's own, and went through all the floors and back on it's own. Maybe a system could be used like this one?

I believe your problem lies to the fact that you need a system pressure that has a capacity to overcome an incoming water with a constant 40 PSI pressure, or/ either you need to lower the pump pressure. In order for your design to work, your overhead tank should produce a gravity fed flow column of water that will exceed or overcome that initial 40 psi pressure created by your pump. When that holding tank bulges, it is an indication that it is absorbing the pumped water pressure nor it is capable of providing large enough flow / pressure to overcome pump pressure and may eventually burst. Try a more rigid tank with a minimum 50 PSI pressure capacity.

If you are DETERMINED to use that set up as it is, ( without changeing much ) you should add a pressure regulator between the pressure tank and the storage tanks ( to LOWER the pressure enough so the tanks are not under too much stress) , then you should add a water pressure booster pump between the storage tanks and your water heater ( to suck the water OUT of the storage tanks and boost it up to " domestic" pressure again.

I agree with Pradeep44 that changing the inlet and outlet is a critical point - if you can resolve the pressure issues and remember you are risking a breach.

Since heat rises and cold sinks, your inlet/outlet setup is contributing to the problem and obstructing the flow you would obtain naturally by convection. The heat that you may get from solar gain will be from the top, also. So you will always have a warmer layer on the top, this is what you want to draw off to your heater anyway, not the cold layer below.

Your second thought about using the tanks for passive solar gain is not a bad idea either.

Amazing responses to a perplexing issue. Thank you all for your input. We have lowered the water level, and hence, pressure in the tanks and decided to use them as passive solar until we finish our apple harvest and have time to work on the system. Then we will try switching the input and output pipes and increase the size of output. Still looking into pressure regulators, ballcocks and any other method than enhances the energy efficiency and sustainability of the system. We have a sink in the sunroom (on the same level as the tanks) that we want to use for watering plants in the room. Thinking about plumbing the tanks to provide solar warmed water to the sink and not try to run it into the hot water heater to feed the whole house (pity though, we were so excited about the prospect). Still wouldn't be gravity fed but perhaps we could use a small battery powered pump to pump the water from the tanks to the sink and use our solar charger to keep the pump charged. Doesn't make sense to use extra energy to run pumps in order to save energy. Just some thoughts on our end. Continuing thoughts, ideas and instructions from your end are very welcome.

Once you lower the water pressure to the holding tanks at the well motor pressure switch by installing a float cut-off switch in the sun porch holding tanks to simply keep them full, you could use a DC water supply pump from a motor home with power supplied from a single 12volt marine trolling battery (deep cycle) kept charged by a solar charger sitting on the roof of the sun room.

This DC water supply pump would feed 'warmed' water to the water heater, porch sink and the whole house probably if you bought this or the next size up:

http://www.rvupgradestore.com/Quad-II-Water-Pump-32-GPM-12V-p/86-8327.htm

Using the tanks as passive for a while will give you some firsthand information about how well they function as a heat collector, and consider whether there is enough surplus heat being stored in them to effectively transfer heat to the water supply.

I wouldn't underestimate the value of plain passive heat storage, until you have seen how well these masses work to moderate temperature extremes during the winter. This is surprisingly effective even at heat transfer/storage rates which are not noticeable in themselves (ie the larger storage mass doesn't become 'hot' to touch at any time).

If the tanks actually do heat up to the point where the heat of the water is noticeable and (if so, likely) generating some unwanted pressure on the tank, then you could use the classic boiler design, which runs water through a coiled pipe inside the tank, to transfer heat from the tank to water in the pipe, and gently warm your plant-watering supply that way while cooling your passive mass. For effective heat transfer by this design, you would want a significant difference in temperature between the tank water and what is piped in.

For a real heat gain to the domestic hot water supply, though, direct solar gain to a pipe coil or array is the way to go, as others pointed out - you will end up with really hot water going into your tank on a sunny day, and big savings. So keep your eye out, and I hope the material you need for that turns up to be salvaged as well.

I have some similar design issues in my home, so I have been thinking about this for awhile (no material to get down and do it as yet). I also thought about making an insulated cooler on the way, out of cold water pipe coil/array from that icy well, in the area it has to pass through to get to the solar heating place. Just a thought...