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solarhotairpanels · 12-10-14, 04:50 PM

Sunspot...

Just some food for thought.. and I don't want to get anyone mad at this forum for stating otherwise but... thru my own experience and Dr. Ben's Online design of a drainback system...

Oxygen entering copper pipes over time can damage internal pump parts without a doubt.. however we are talking years here for this type damage to occur as far as I've read.

It's very important to remember on a drainback system that a vacum lock does not occur inside the piping during drainback to the tank.

If when the pump shuts off the water is vacum locked, all of the water will not drain back to your storage tank.... thus the remaining water outside in the pipe or collector could FREEZE causing all kinds of issues.

So note.. my findings are that...
You have to allow some air to enter the pipe when the pump shuts down.

Many DIY drainback tank designs similar to yours has the collector return pipe enter the top of the tank but does not allow that pipe to touch the water when the tank is at it's most full level.

This way.. when pump shuts down and water begins to return, air is sucked into that pipe allowing the water to flow freely in BOTH directions. Down the return pipe and also back down the pipe thru the pump.

The other thing that can cause a problem is what I mentioned before to you is the check valve inside your collector pump.

If your pump is so equipped...That valve can stop water from returning back down the pipe THRU your circulator pump. The valve would have to be removed to allow free flow back thru the pump. Know what I mean?

Some pumps have the valve in there to keep the pumps primed with water for next startup...

Example: Let's say the collector pump was mounted ABOVE water level. (NOT RECOMENDED)
When the pump shuts down the pump would stay primed with water in order to pump that water UP at next startup.

In drainback systems the circulator pump should be mounted 'below storage tank water level' so they stay primed automatically with NO check valve installed or needed.

12-10-14, 04:50 PM	#31
solarhotairpanels Helper EcoRenovator Join Date: Mar 2012 Location: Warwick, Rhode Island Posts: 92 Thanks: 22 Thanked 29 Times in 18 Posts	Sunspot... Just some food for thought.. and I don't want to get anyone mad at this forum for stating otherwise but... thru my own experience and Dr. Ben's Online design of a drainback system... Oxygen entering copper pipes over time can damage internal pump parts without a doubt.. however we are talking years here for this type damage to occur as far as I've read. It's very important to remember on a drainback system that a vacum lock does not occur inside the piping during drainback to the tank. If when the pump shuts off the water is vacum locked, all of the water will not drain back to your storage tank.... thus the remaining water outside in the pipe or collector could FREEZE causing all kinds of issues. So note.. my findings are that... You have to allow some air to enter the pipe when the pump shuts down. Many DIY drainback tank designs similar to yours has the collector return pipe enter the top of the tank but does not allow that pipe to touch the water when the tank is at it's most full level. This way.. when pump shuts down and water begins to return, air is sucked into that pipe allowing the water to flow freely in BOTH directions. Down the return pipe and also back down the pipe thru the pump. The other thing that can cause a problem is what I mentioned before to you is the check valve inside your collector pump. If your pump is so equipped...That valve can stop water from returning back down the pipe THRU your circulator pump. The valve would have to be removed to allow free flow back thru the pump. Know what I mean? Some pumps have the valve in there to keep the pumps primed with water for next startup... Example: Let's say the collector pump was mounted ABOVE water level. (NOT RECOMENDED) When the pump shuts down the pump would stay primed with water in order to pump that water UP at next startup. In drainback systems the circulator pump should be mounted 'below storage tank water level' so they stay primed automatically with NO check valve installed or needed. __________________ Pat from Warwick, RI Please Note: Comments and/or suggestions I make here at the forums on 'your' projects as well as my own have all been carefully and scientifically calculated by 'the seat of my pants' To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts. Last edited by solarhotairpanels; 12-10-14 at 04:53 PM..