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everlearning
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Posted: Thu Aug 7th, 2008 07:33 am |
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Larry,
Should I continue to keep the shut off valve to the radiator in a shut off position?
I love having a good hot shower, but won't leaving it off create the very problem re standing water that you warned me about ?
JillLast edited on Thu Aug 7th, 2008 07:35 am by everlearning
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eleent
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Posted: Thu Aug 7th, 2008 08:13 am |
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Hello: The pressure you found is good and would suggest there is no reason why the T&P would "pop off". So, something unusual must happen. Perhaps there is a check valve or backflow preventer in the line, so as water expands when heated, pressure goes up until the T&P lets go. Maybe? An expansion tank could help if there really is a check valve of some sort that needs to stay.
About bacteria. The closed valve test was only a test, not anything long term. You now know that ghost flow was the problem and have two possibilities for the fix. One is to install a heat exchanger and pump along with controls to completely separate the systems in a fail safe way. The other possibility is to install check valves to prevent ghost flow and a timer to pump daily for only a few minutes. This should keep the squatter legionnaires bacteria from camping out in the plumbing. One way has more risk and less cost. If you're watchful though, there won't be a problem.
As to the shutting down of the heater on higher temps, I don't have an easy answer. There should be info in "Tanklets" at the top of the forum, which could help. Dust, lint and such stuff can clog up a heater's air intake 
Yours, Larry
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elenano
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Posted: Thu Aug 7th, 2008 04:31 pm |
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OK. You're OK on static line pressure. Anything over 80 psi is bad, but you're well under that. The next test to make: when you know nobody is using hot water, make the tank fire by turning up the thermostat and watch the pressure gauge. If it spikes significantly over 80, then you have thermal expansion and that is making the T&P open. The solution to that is an expansion tank.
Randy Schuyler
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everlearning
Member
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Posted: Fri Aug 8th, 2008 03:53 am |
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Larry,
You say
"The pressure you found is good and would suggest there is no reason why the T&P would "pop off". So, something unusual must happen. Perhaps there is a check valve or backflow preventer in the line, so as water expands when heated, pressure goes up until the T&P lets go."
Do you mean a check valve other than the one that is on the cold water line?
(I'm attaching the drawing - now corrected, hopefully - for ease of reference since we're now on a 2nd page.)
Also, you mention blockage of air flow... Perhaps that's the problem. We've got mice, and when I first went into the shed where the tank is, the top of the tank was thick w droppings and debris from the mouse/mice. I've cleared most of it away. (I planned to vacuum it to get the droppings completley clear, but just hadn't gotten to that yet.)
If we put check valves in, to prevent bacterial problems, where should they go?
Should we replace the present cold water check valve with a spring check?
and/or Should we re-plumb the cold water line where the present check valve is to some configuration so that the check valve (or spring check) is horizontal?
Where would a timer go in all of this?
I'm familiar w lighting timers that plug into electrical outlets, but what kind of timer makes the water recirculate? Would it be turning on the thermostat? Oh, wait...., is it that one replaces the thermostat with one that has a programmable timer?
JillAttachment: plumbing drawing, revised.jpg (Downloaded 25 times)
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eleent
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Posted: Fri Aug 8th, 2008 04:32 am |
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Hello: In order... The check valve in the cold line now doesn't work. Gravity says that it must stay open  To the water, that check is just a piece of pipe. The problem is elsewhere.
Air flow for combustion usually enters at the base of the heater, then up and out the vent pipe. Anything that affects/limits that flow could affect combustion. It is a pretty big area of study... lots of possible factors.
Spring check valve/s should go in the heating loop. They will help stop ghost flow, forcing water to go only where it should rather than where it wants to go.
Do not replace the present swing check (that doesn't work) with a spring check. Just remove it. If a working valve were there, you would get thermal expansion problems for your effort
The pump on the heating loop would plug into a grounded timer. They are about $15 and are called appliance timers.
A thermostat and the timer should each be able to turn on the pump independently. This allows daily flushing and provides heat when you need it.
Yours, Larry
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everlearning
Member
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Posted: Fri Aug 8th, 2008 08:42 pm |
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Larry,
OK! So to be clear and specific, so I get this right... re the valves and piping...
Should we install 1 or 2 spring check valves into the hot water line?
Where in the hot water system would it be best to place the spring check valve/s. Would it be one on the line to the radiator (but after the shut off valve) and one on the line away from the radiator???
Is it better if they are on a horizontal pipe line and if so, would be still go with a spring check valve.
Should we add an additional shut off in the hot water line? (You mentioned earlier that this would be helpful). Where? Right after the hot water leaves the tank, before it goes to the bathroom? Or just before it returns to the tank?
re the timer,
When the timer goes on and recirculates in the summer, it will have to do so with hot water, so there will heat given off, but if we set it for the middle of the night, given the climate here, that won't matter. So that problem is solved too.
Love that we are going to solve this!
JillLast edited on Fri Aug 8th, 2008 09:52 pm by everlearning
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everlearning
Member
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Posted: Fri Aug 8th, 2008 09:15 pm |
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Randy,
I did the next pressure gauge test per your suggestion.
With no one using or having used hot water, I turned up the thermostat on the radiator so that the radiator called for hot water. I heard the heater fire up; I heard the water circulating; and I could feel the return pipe heating up. I stayed watching for 5 minutes plus.
The pressure held at 50 psi. No spikes whatsoever.
I left the gauge in place and let the whole thing stay running. After 45 minutes, the psi was at 54.
This was with the heater set at 2 settings higher than the 120 mark.
(By the way, I've had the water heater at that setting for at least 2 days now, with no TP release or shutting off. One day was with the hot water shut off to the radiator and one day was with the hot water shut off valve open, but with the radiator not being asked for heat.)
I'm thinking to put the heat all the way up to High tonight, to see what happens. What do you think???
Jill
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everlearning
Member
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Posted: Fri Aug 8th, 2008 09:38 pm |
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Larry,
Also, could you explain how ghosting works? I can't get my head around the mechanics of it... the flow of it... how it works. And I'd like to understand it.
Backflow allows cold water to mix in... so the water flows back into the tank from where? the hot water pipe as it heads out away from the heater, to the bathroom?
And How does something/ anything make the hot water (which is at the top of the tank, right?) mix with the cool water (at the bottom of the tank).
Is it that the pipe that is supposed to take the hot water out of the tank, from the top, is no longer pulling the water out but instead is putting water back into the tank from the radiator? which would mean, wait, maybe i've go it, it would have to pull water from that pipe that was the return to the radiator... which enters near the bottom of the tank (see drawing). Is that it? Have I got it??!
JillLast edited on Fri Aug 8th, 2008 09:47 pm by everlearning
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