Hydor External Heaters

[dave_oddballs]

hi, been shopping around for external heaters as i am expecting rays in my tank soon.
the thing is they say they should be attached to the outlet of the external filter. on my tank (284 gallon) i have 2 eheim pro 3 2080 filters, they each have 2 inlets and 1 outlet, thus giving me only 2 outlets onto which to connect the heaters, but i need 3 of them to heat the tank.
the only think of putting 2 heaters in line on one of the filter outlets and just the 1 on the other, but will they work properly having them in line like that??
any suggestions
cheers,
Dave

 

[ellena]

What's the reason they have to go on the outlet, not the inlet?

 

[dave_oddballs]

i honestly don't know any reason why they couldn't be fitted onto the inlet apart from maybe while in the filter the water has chance to cool down before it reaches the actual tank whereas the heater being on the outlet it is heated then immediately enters the tank.
my thoughts are that the only way to do it is to put 2 in a row on one of the filter outlets but then still the water is still going to be heated as much as the last heater heats it, if you get what i meen.
im struggling to come up with other options there may be!

Dave

 

[bobross]

Why can't you put one heater on the inlet and one on the outlet of one filter? Then put the remaining heater on the outlet of the other filter?

I've never used external heaters so I have no experience with them. But if they sense temperature and turn on and off like an internal 'normal' heater, here's my question.

Whether you run two in a a row(your suggestion), or you try my suggestion, either way, won't the 2nd heater hardly turn on? Does that make sense? I have the image in my head of what your thinking of doing and I see that 2nd heater in a row barely turning on.

I think you should go buy some extra tubing for your filters and try all of the configurations you can think of and go from there. That way, your not cutting up your filters tubing for an idea(s) that might not work.

BobRoss

By the way, AWESOME tank man

 

[dave_oddballs]

thanks!
yeah but my thinking is that if i have a heater on the filter inlet, the heated water will cool down whilst in the filter then the heater on the outlet will 're-heat' the water before it enters the tank,making the heater on the inlet insignificant, in my opinion giving the heating power of just the single heater on the outlet.

 

[bobross]

That makes sense, I guess. It's funny you say that. That was the same reason that I haven't bought one of Rena's external heaters. If I understood them right, you could use them alone in the tank or you could replace your inlet pipe of a Rena Smartfilter or an xp series filter with it. I didn't go with it because I thought the same thing.

Surely, the water isn't sitting in a filter long enough to cool down, is it? I understand your hesitation that's why I thought you could use some extra tubing to try it out.

It's too bad you couldn't add like a pvc y or something to one of the outlets and that way you could have two outlets. But I assume that wouldn't work to well since the water would take the path of least resistance, and the additional outlet wouldn't work too well. Does that make sense?

I wanted to ask this since I feel too lazy to look it up, but what's with rays and heaters anyways? Will they burn themselves on them or break them?

Why couldn't you just get a guard for one of the heaters and mount the two externals on your filters?

BobRoss

 

[hunter001]

Could it be anything to do with dirty water passing through it if you have it on the intake? Maybe its more likely to get a build up of gunk and thats why they recommend you use it on the outlet as there should be only clean water passing through. If there is a build up of anything theres potential for it not to perform as well as it should. I could be completly wrong but its just another idea to add to the mix.

 

[OldMan47]

I would suggest 2 reasons that you want the heater on the return leg rather than the inlet. First the inlet is nothing but a siphon and it has very little ability to overcome any flow restrictions. Second, the warmer water is harder for the impeller in the filter to pump. It is almost like not having the filter far enough below the tank water level when the water is hotter. The impeller needs a certain amount of suction pressure to pump properly and that pressure is the amount that the impeller sees over and above the boiling point of water at that pressure. As the water gets warmer, the distance to the boiling point at reduced pressures can get too small and cause the impeller to cavitate. Warmer water and a suction flow restriction will put a double effect on the impeller, not a great way to go unless the filter is well lower than the minimum suggested by the manufacturer to make up for the loss caused by a heater in the inlet. For my canister, they recommend at least 2 feet from the water line to the top of the filter but allow up to 3 1/2 feet of height difference. I would no way go less than 3 feet for my filter in a suction heater situation. The extra foot of suction head would probably be enough to overcome that double whammy on suction pressure.

 

[Ren&Stumpy]

I got a 500w eheim pro 3 thermo 2180 for sale collection only though, heating problems solved

 

[Liam50]

you could have two hydor externals on the outlets and possible the heater that sits in the tank on the end of input line. its called a rena smart. also can't you use the fluval e- series they are completely covered.

 

[raptorrex]

What's the reason they have to go on the outlet, not the inlet?

could it be because Hydor state, in their instructions, it should be on the outlet side? the reasons for this are covered by OldMan47's post.

 

[bobross]

http/www.aquatichouse.com/Pumps_files/Rena%20heaters.asp

I'm trying not to argue about this, I just can't wrap my head around the difference between location of the heater if it's an option offered for both inlet & outlet. Whether Rena or Hydor(I'm sure there are other options) it has to be possible.

I can't see how water at, say, 76 degrees does more harm to in impeller vs. heated water going into the filter.
Again, I'm not arguing, I don't understand the relevance of it is a comparison, that's all. I will sit back and see what Dave decides to do, since I don't know what else to suggest. I'm sure I didn't contribute to this anyways.


BobRoss

 

[kiriyama]

http/www.warehouse-aquatics.co.uk/aquarium-heaterschillers/hydor-external-thermal-heaters/hydor-eth-external-thermal-heater-200w-p-3878.html
you might find something on here

 

[raptorrex]

http/www.aquaticho...a%20heaters.asp

  I'm trying not to argue about this, I just can't wrap my head around the difference between location of the heater if it's an option offered for both inlet & outlet.  Whether Rena or Hydor(I'm sure there are other options) it has to be possible.  

I can't see how water at, say, 76 degrees does more harm to in impeller vs. heated water going into the filter.
Again, I'm not arguing, I don't understand the relevance of it is a comparison, that's all.   I will sit back and see what Dave decides to do, since I don't know what else to suggest. I'm sure I didn't contribute to this anyways.


BobRoss

I see your point. but the reason has been explained, by OldMan47. all you need to do is research his comments.


if you ask, often enough, you will find somebody thats says "its ok, put it on the inlet side". that wont make them right, though.

 

[Rooster]

Are you SURE you need more than one to do the job ? If so, then just add them in series... IN ONE OUTLET !