Outdoor Wood Furnace Info
All-Purpose OWF Discussions => General Outdoor Furnace Discussion => Topic started by: trz on March 18, 2016, 03:13:40 PM
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Having an issue with hot water. It seems it's never real hot but it is hotter sometimes more than other times. I think when we don't use it real often then when we do use it it is not very hot. Wondering if it would be losing heat sitting in the water heater. Anyone have that happen?
I have a Hawkin Energy 1100
Domestic cold water comes in, enters top side of 30 plate w-w heat exchanger exits bottom from there it enters cold side of water heater exits hot side then into mixer valve and on through the house. Mixer is set at hottest setting.
Any thoughts?
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in my opinion, you might as well leave power on to the hot water tank, it does not take much power to keep your water hot once there, the high cost of energy is to heat it from 50 degrees to your desired tempature there are other options but this is the easiest in my opinion as you are already plumbed up and running.
if you use very little hot water you could just bypass the hot water tank and use the plate exchanger to deliver "on demand"
add a small pump and circulate
add a thermo-syohon
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get a sidearm
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When was the last time you cleaned the flat plate?
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While the OWB is up to temp, turn on a hot water faucet and then feel how hot the pipe is going into the tank and also out of the tank into the mixing valve. If it is real hot going into the mix valve, that may be the problem.
If you have a gas water heater and it sits a lot between usage then it can cool down a lot. Natural vent water heaters are the worst.
Like mentioned above, you can add a recirc pump or sidearm.
Or if you have a humidifier, hook it up to hot water and it will keep the water heater hot.
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It's an electric water heater if that makes any difference.
I'm not familiat with what a sidearm is i'll have to do some research.
Actually i do use a fair amount of hot water but, it sits all night and in the morn its not very hot.
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Electric don't lose much heat because they don't have a vent up the center.
You shouldn't need a sidearm though. Your setup should work fine.
If your 30 plate around 5x12 inches? Also if you do the test running hot water, also check the boiler pipe after the plate. If your pump is too small or the plate is getting plugged it will probably be fairly cold.
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How is OWB plumbing (hot water) set up to get to the exchanger and DWH, and how is it plumbed from there?
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I have a 20 plate running into the top of the electric water heater and it works great. I have my boiler set point at 190 degrees. What's your at? If it's too low that may explain it.
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I had a check valve in the top of my electric hot water tank that caused my hot water to be very hot, cold and or tepid.
Removed the check valve and no issues since.
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get a sidearm
Ditto,,,, I had no luck with the plate.
Or use them in tandem
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So, how do you clean a plates?
Did the check with hot water running, pipes are not a whole lot of difference going into the tank, coming out of the tank or after the mixing valve. At least not what i can feel by hand!
Checked the water in my tank with candy thermometer it read about 120. Checked the water from the boiler as soon as it enters the house it was about 142.
Went out to the boiler and water temp gauge read about 170( cant't believe i'm losing 30 between boiler and house)!
Looked at humidistat and through the little window set on 160, but i don't know what the differential is. How do i tell?
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Not humidistat, meant aquastat!
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Check the temperature of the boiler pipe before and after the plate while running hot water. If the boiler water coming out of the plate is fairly low then you probably need a larger pump or remove some restrictions.
How did you check the boiler water temp in the house? If through the pipe, you should do the same at the OWB end.
What brand is your OWB?
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So, how do you clean a plates?
Did the check with hot water running, pipes are not a whole lot of difference going into the tank, coming out of the tank or after the mixing valve. At least not what i can feel by hand!
Checked the water in my tank with candy thermometer it read about 120. Checked the water from the boiler as soon as it enters the house it was about 142.
Went out to the boiler and water temp gauge read about 170( cant't believe i'm losing 30 between boiler and house)!
Looked at humidistat and through the little window set on 160, but i don't know what the differential is. How do i tell?
I use a short piece of garden hose wit two female ends, a five gallon bucket and a puddle pump with the garden hose adapter on it. Hook your garden hose to the flushing valves, the other end to the pump, place the pump in the bucket, add your cleaning solution ( i use white vinegar) then place another short hose from the other cleaning t into the bucket, then plug in the pump and let run.
Heres a picture from my setup.
(https://scontent-ord1-1.xx.fbcdn.net/hphotos-xft1/t31.0-8/12792133_10206740900815528_3098981650032687019_o.jpg)
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Move the plate hex from the cold to the hot supply line so you are not dumping the hot water leaving the plate into the water heater. When you turn on any hot fixture the water leaving the water heater will flow through the plate hex directly to the fixture and deliver very hot water, always temper with a mix valve. Make sure the fluid flow in the hex between the boiler water and dhw are in opposite directions.
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I would not move the heat exchanger. If the water entering the water heater is not a lot of difference from the exit you will not gain much. mlappin is right on cleaning the heat exchanger. RSI is right on needing to check flow from the boiler. Check your temp where it leaves the boiler the same way you check it at the house. Hawken is built on the old Global design and I have seen Global units with poor circulation within the stove and exit water not as hot as aquastat reading, not saying this is happening but I would check it.Also if the heat exchanger is plugged tight on some of the slots, the cleaner will not get it. It will only clean the slots that are at least have some flow.
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Went through all this crap myself.
Sidearm solved my problem.
86 the plate!!!
http://outdoorwoodfurnaceinfo.com/forum/index.php?topic=6915.0
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What sidearm do you use?
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We have installed for quite a few dairy farms that need very hot water for equipment washing two to three times a day. Because of the large daily process heat demand most all of them burn year round. We found the best way to meet this demand is to put the plate hex on the hot side bypassing the tank. Been doing it for years, works great. Also install the same way for our residential customers but always include a mix valve. In a plate hex fluid flow must be in opposite directions or it will be ineffective. If the plate is plugging up that is a different issue. Cleaning the plate often to keep a proper flow rate can be a pain, so a side arm could be the answer. We still use side arms in certain situations, usually 80000 btu for residential.
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We have installed for quite a few dairy farms that need very hot water for equipment washing two to three times a day. Because of the large daily process heat demand most all of them burn year round. We found the best way to meet this demand is to put the plate hex on the hot side bypassing the tank. Been doing it for years, works great. Also install the same way for our residential customers but always include a mix valve.
Thats pretty much what I did with mine, I also use a sidearm as an experiment to see just how much heat a sidearm can pull out of the boiler water. Works reasonably well, most of the time the sidearm can keep up, I have an aguastat that starts the pump for the secondary loop for the DHW anytime the water is below 140 coming out of the water heater. Water that is heated by the sidearm leaves the hot water heater and enters the plate, if temp is high enough no problem, if not the pump on the plate secondary loop starts.
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You have pinpointed your problem. You have no way to reheat the water once it makes its way into the 40 gallon heater. While you could get a $300 side arm, you could also hook your plate up as a thermosiphon the same as you would a sidearm.
Pipe in a loop from the bottom of your electric heater and connect it to the top, where the relief valve goes. Do not remove the relief valve, just install a brass T fitting under it. This allows the heated water to return to the tank while stopping it from "short circuiting" . The bottom connection (to the plate) can just tie into the cold water intake of the tank. As long as the plate is mounted lower than the tank, it will thermosiphon and fill the tank with hot water, but that water can wind up at the same temperature as the OWB unless there is a mixing valve.
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If it has never worked right since it was new then it is probably not a plugging problem.
You could get a sidearm but adding a recirc pump would be easier and cheaper and work better. There is another problem with the system though which would be better to fix that changing out the hot water heat exchanger.
Also, if the water heater is fairly old, there may be a lot of sediment built up inside that could plug a sidearm fairly quick. Electric water heaters are usually worse for that too.
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Where would i find a recirculating pump and how is it plumbed in?
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Patvetz
Wish i had a diagram of that!
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Put a tee before the plate hx and one either at the drain or another place in the tank. Lower will get better circulation. Then pump water from the tank to the tee before the plate HX.
Have you checked the temp of the OWB water after the plate hx when the hot water is running? You should really make sure you have enough flow.
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Wish I could post pictures.... :-[