inline UV and heater?

[fireman731]

Has anyone used the hydor inline heaters on a canister? What do yall think of them?

Also, I want to use an inline UV on a canister, I would like the turbo twist 9W, it says its about 200 GPH flow, so I assume I need a canister filter that matches with an output of about 200 GPH for adequest dwell time for the UV to be effective?

If I want to plumb both the hydor and the turbo twist inline, what order should I do it? The heater before the filter and the UV after? or both after? I think the UV after for sure so it doesn't have debris flowing through it.

[dalto]

I have used the Hydor Eth heaters on most of tanks with canisters. They are great. You just need to remember that they need to be oriented vertically so make sure you have room for that.

I have always put them after the filter to avoid debris going through the heater.

[fireman731]

So does it really matter which order I put them in on the return? I'm gunna have to splice off with a valve for the UV to slow the flow from the canister anyways so I was thinking heating after that would probably be more uniform as opposed to heating the water before it splits off and slows down trough the uv?


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[dalto]

I don't typically use uv since it is not needed in the types of tanks I keep but I can tell you that the heater will benefit from the lower flow rate as well.

[Linwood]

Originally Posted by dalto

I don't typically use uv since it is not needed in the types of tanks I keep but I can tell you that the heater will benefit from the lower flow rate as well.

Why do you say that?

Generally speaking a heater is most efficient when it is passing the most water, as the temperature difference is the greatest.

[dalto]

Originally Posted by Linwood

Why do you say that?

Generally speaking a heater is most efficient when it is passing the most water, as the temperature difference is the greatest.

I believe it needs time to heat the water. Those heaters are actually rated for a max throughput.

Honestly, I am not an expert in heating elements in flowing water. I am mostly going on information contained in the product manual.

[Linwood]

Originally Posted by dalto

I believe it needs time to heat the water. Those heaters are actually rated for a max throughput.

Honestly, I am not an expert in heating elements in flowing water. I am mostly going on information contained in the product manual.

I can't find a max flow rate in the manual that came with mine, nor the FAQ on line.

Heat transfer is this situation (all other things being equal) is directly proportional to the difference in temperature of the heating surface and the media.

There are two problems inherent in water moving too slow across the heater. The first is that if it moves too slowly, it can warm actually too much, and cause the heater to turn off before the tank is warm enough. This can also happen in an in-tank heater if there is too little water flow -- you get a warm area around the heater that turns it off, but the rest of the tank is colder.

That's unlikely with any decent amount of flow of course, but the second issue is always present -- the slower the water moves the higher the temperature of the water that is actually in the tube. This higher temperature means the heat transfer is less efficient; another way to think of it, the heater itself heats up with less water flowing through to cool it. This wasted heat is, well, wasted.

Provided you do not have a flow rate that causes air (or cavitation) to enter the lines, or damages your plumbing, or damages the tank on output, any heater is at its most efficient with higher flow across the heating surface. That's just basic thermodynamics.

All that said, I suspect the difference in efficiency at (say) 50gph (that you might use for a UV kit) and 300gph (somewhat normal canister flow for this size) is extremely small.

But I would be curious to know where you saw a max flow rate?

[dalto]

Originally Posted by Linwood

I can't find a max flow rate in the manual that came with mine, nor the FAQ on line.

But I would be curious to know where you saw a max flow rate?

OK, so, I went back to look at the manual and, of course, as you have already noted it wasn't there.

So I did some searching and found several references to max GPH of 250. However, all of these were of dubious origins. So I reached out to the manufacturer to get an answer. Here it is:

"It is a close loop system so even high flow rates the heater is fine as long as the tank size is in the recommended area."

So....I was wrong

[TomK2]

I have been using an in-line heater for years on my canister outflow. Think I got one the first year they came out? They require vertical orientation, and the one I bought years ago is thicker than the tubing, so you need room for it to be behind the tank and between the wall, if that is how you are going to have it. I have always had to set the temperature on the dial higher than what I wanted. 78 to get 72, 84 to get 78. I have had filters fail, and the in line heater would cycle on and off and not burn out with zero flow. I had turned a filter off planning on tearing down a tank, forgot about the heater, and over a month later it still works (hey, I got busy!) . If you use canister filters they are nice. I would replace this one if it quit.

Sorry, no UV advice to give you.

[TomK2]

I might have to retract what I said about the in line thermostat. Just discovered that my thermometer was reading low. Hmmm. Bought two new thermometers which agree, old one reads 6 degrees lower. I wonder how long THAT was going on. Glad I needed some new ones, and decided to test my highest temp tank.