DIY Project DIY Inline heater

[Tanksy]

Hello everyone.

I hate having the heater in the tank. It's a blot on the landscape. Buying an inline heater was not an option for me. The smallest one out there is 300W. A bit of an overkill for my 30 lt tank.
So I thought I should build a DIY one. This thread could be handy to someone who wants to build one themselves.

This is the design. The tube in the centre is going to be transparent, so that I can check if the heater's on or off.



And her's the parts.



The actual heater's going to be a Visitherm 150W. The main tube is transparent, so that I can check if the heater's on or off. All PVC parts will be glued with cement. I'm going to use aquarium silicone for the transparent tube. The end caps are threaded. Makes life easier for cleaning it.

Cheers!

 

[Tanksy]

Parts list:

• 3/4 inch Uniseal (fits any heater with 25mm tube diameter)
• 1 inch PVC pipe (length depends on the size of your heater)
• 1 inch BSP threaded blanking cap (X2)
• 1 inch PVC 45 degrees Tee section
• 1 inch socket to 1 inch male adaptor (X2)
• Tefen Nylon straight hose connectors (size depending on your project) (X2)
• Tefen Nylon end caps (to fit connectors) (X2)
• Aquarium silicone
• PVC/ABS solvent cement

 

[Tanksy]

Test fitting with the heater I'm going to use. Decisions, decisions...

Should I leave the clear tube as it is, or cut it closer to the heaters length?

 

[dw1305]

Hi all,

Should I leave the clear tube as it is, or cut it closer to the heaters length?

I don't know, but I'll add Marcel (@zozo ) in because I know he has <"practical experience of building these">.

cheers Darrel

 

[zozo]

The design is ok... 🙂 I guess the length of the tube doesn't matter that much, a few inches shorter or longer won't make that much of a difference. The clear tube is a nice touch but it will not stay clear very long, the tube will grow a sticky biofilm and probably get dirty within a few weeks. Then you probably will not see the heater light when it's on.
It would be more convenient to use an extra external thermostat for that after you get tired take it apart and clean it all the time.

Then take a thermostat that uses a 10K NTC thermistor and replace it with one like this. And set the heater to 27°C and the external thermostat to 25°C for example.
www.aliexpress.com/i/4001174388575.html

And also place this in line at the feed side of the heater. Drill a hole in the tube and tap the M8 thread in the tube and seal the thermistor with some Teflon. 🙂

 

[Tanksy]

The design is ok... 🙂 I guess the length of the tube doesn't matter that much, a few inches shorter or longer won't make that much of a difference. The clear tube is a nice touch but it will not stay clear very long, the tube will grow a sticky biofilm and probably get dirty within a few weeks. Then you probably will not see the heater light when it's on.

Well, turned out the light of the heater won't be visible as it's sitting in the grey PVC Tee. 🙄
Maybee I could drill a hole and glue a piece of clear acrylic rod.
I know the clear tube won't stay clear very long. It'll be behind the cabinet, so I can live with that.

It would be more convenient to use an extra external thermostat for that after you get tired take it apart and clean it all the time.

Then take a thermostat that uses a 10K NTC thermistor and replace it with one like this. And set the heater to 27°C and the external thermostat to 25°C for example.
www.aliexpress.com/i/4001174388575.html

And also place this in line at the feed side of the heater. Drill a hole in the tube and tap the M8 thread in the tube and seal the thermistor with some Teflon. 🙂

Great idea! Is there a thermostat you'd recommend?

Cheers!

 

[zozo]

Is there a thermostat you'd recommend?

Depending on your DIY skills with electronics there are quite a lot of options out there from various brands, most of them use an NTC 10K sensor. If you search Aliexpress or eBay for Temperature controllers you'll find a lot in acceptable price ranges. just make sure it has a 10K NTC you can replace.

For example, if you like to go easy on yourself with plug and play.
www.aliexpress.com/item/32898240902.html

The ones i did build in the past all were DC 12 volt heaters and thermostats... I have no experience with the AC220 versions. But in principle they are similar.

 

[Guest]

How’re you attaching the heater to the pipes?

 

[Tanksy]

Depending on your DIY skills with electronics there are quite a lot of options out there from various brands, most of them use an NTC 10K sensor. If you search Aliexpress or eBay for Temperature controllers you'll find a lot in acceptable price ranges. just make sure it has a 10K NTC you can replace.

For example, if you like to go easy on yourself with plug and play.
www.aliexpress.com/item/32898240902.html

What if I bought an Inkbird and replaced the probe with the one you linked above. Would that work?

The ones i did build in the past all were DC 12 volt heaters and thermostats...

This statement is useless without links 😝

 

[Tanksy]

How’re you attaching the heater to the pipes?

Siliconed fittings to the end caps.

 

[zozo]

What if I bought an Inkbird and replaced the probe with the one you linked above. Would that work?

Sure! The most common thermistor is the 10K NTC if the inkbird has this you're good to go... 🙂

This statement is useless without links

I'm sorry I never recorded the final build, but it was pretty similar to yours only used a 12 Volt heater cartridge instead plugged in a switching PSU from a computer with a DC 12 volt thermostat. You can see some pictures of it in the very first journal I posted here at UKAPS.

My first - "3 of life" :)

Finaly! A journal.. :) hope you like it. how did it all started? it all began with purchasing a eledged Pygmae Nymphaea via ebay. I kept in the house for a while in a bowl of water. I didn't realy suite this lovely plant and after 25 years out of the hobby i decieded to step in again and to...

www.ukaps.org

I do still have a picture of the very first experimental build that didn't work out as intended it didn't have enough power and some design flaws.

Later I did build a more sophisticated stronger version I never recorded the build from it... AFAIK the 12-volt heater cartridges are sold out at the time. But I also have them no longer in use. Tho it worked a charm for quite some years.

 

[Tanksy]

Sure! The most common thermistor is the 10K NTC if the inkbird has this you're good to go... 🙂

Couldn't find what type of probe the Inkbird has. But I found out that the Elitech STC-1000Pro has a 10k NTC sensor, so it's an easy swap I guess.

 

[ian_m]

Siliconed fittings to the end caps.

Silicone is no good for a permanent fixing. There are very few things that silicone actually bonds to, the majority of plastics is one of them. Treat the silicone as a "thread sealant" rather than a glue.

You need to solvent weld to do it properly, obviously ensuring both plastics you are "welding" are compatible with the solvent weld. Some plastics will weld OK, but then suffer "crazing" as the solvent evaporates.

 

[Tanksy]

Silicone is no good for a permanent fixing. There are very few things that silicone actually bonds to, the majority of plastics is one of them. Treat the silicone as a "thread sealant" rather than a glue.

You need to solvent weld to do it properly, obviously ensuring both plastics you are "welding" are compatible with the solvent weld. Some plastics will weld OK, but then suffer "crazing" as the solvent evaporates.

I couldn't find PVC or ABS fittings at the time (except from China). That's why I bought Tefen/Nylon fittings. I guess the proper way was to tap a thread, if I had the tool.
Anyway, it's not actually glued. The fitting goes snugly through the hole and a nut holds it in place. Silicone is applied on both the outside and the inside of the end cap.
I thought that would do the trick.

 

[ian_m]

I couldn't find PVC or ABS fittings at the time (except from China). That's why I bought Tefen/Nylon fittings. I guess the proper way was to tap a thread, if I had the tool.
Anyway, it's not actually glued. The fitting goes snugly through the hole and a nut holds it in place. Silicone is applied on both the outside and the inside of the end cap.
I thought that would do the trick.

Try taking it apart, I expect you will find you will be able to peel off the silicone with a finger nail, proving it hasn't actually stuck to the plastic.

Some epoxies glue nylon very well, but you need to check will they glue PVC as well.

What happens with "non glued silicone" is over a period of a year or two the water slowly creeps along the joint and peels the silicone off. I know this very well in trying to make waterproof joints in LED tape, after a year or the water from condensation worked its way along the silicone/pvc cabling joint and corroded the copper in the LED tapes.

Some "neutral cure" silicones, I have used, do appear to stick quite well to plastic.
RS PRO White Sealant Paste 100 g Tube | RS Components

Gorilla glue also tends to bond to plastic quite well.
Gorilla Glue 115ml

Not sure what the solution is ? Use silicone ?

 

[zozo]

Why not use the proper parts?... 🙂 I actually do not know the English names for them so I show a picture...

Try to find a local pond shop, they should have all you need... 🙂

 

[Tanksy]

Try taking it apart, I expect you will find you will be able to peel off the silicone with a finger nail, proving it hasn't actually stuck to the plastic.

Actually, I've already tried that. Silicone sticks pretty good to PVC. I dare say, as good as it sticks to glass.
I'll give it a try with Tefen and let you know.

Why not use the proper parts?... 🙂 I actually do not know the English names for them so I show a picture...

I think the first photo is a PVC BSP reducing socket. I couldn't find a 1''x'1/2'' anywhere in the UK though.
The second one is a PVC hosetail or hose adaptor. Again, couldn't find a 12mm x 1/2''.

 

[zozo]

I think the first photo is a PVC BSP reducing socket

No, it actually isn't a reducer. 🙂 it's a conversion plug to glue into a socket... In my country, the outer diameter is for example metric 32mm female with 1/2" BSP internal thread, but they come in different kinds of sizes metric pipe size / imperial thread. They are pretty standard parts in the PVC coupling trade, Literally translated we name it a Screw Bush... But I'm at a loss if this would be the English term for it.

Could be in my case I have a pond shop next door that has them in all regularly used sizes and the internet is littered with them if would like to order it.

Somehow I can't imagine it to be difficult to source in the UK, since it is not the end of the world.

Edit: think I found it...

We’re Irrigation Experts | Advisors And Installers | Plantex UK

The leading supplier of high quality commercial irrigation systems for top fruit and soft fruit growers, vineyards, sports grounds and commercial landscapers.

plantexuk.com

It's indeed a reducing Bush Metric x imperial female thread. 🙂 Thus you would need a piece of pipe with a socket and in this socket the reducing bush instead of a piece of pipe with a cap with a drilled hole etc.

We’re Irrigation Experts | Advisors And Installers | Plantex UK

The leading supplier of high quality commercial irrigation systems for top fruit and soft fruit growers, vineyards, sports grounds and commercial landscapers.

plantexuk.com

We’re Irrigation Experts | Advisors And Installers | Plantex UK

The leading supplier of high quality commercial irrigation systems for top fruit and soft fruit growers, vineyards, sports grounds and commercial landscapers.

plantexuk.com

 

[Tanksy]

No, it actually isn't a reducer. 🙂 it's a conversion plug to glue into a socket... In my country, the outer diameter is for example metric 32mm female with 1/2" BSP internal thread, but they come in different kinds of sizes metric pipe size / imperial thread. They are pretty standard parts in the PVC coupling trade, Literally translated we name it a Screw Bush... But I'm at a loss if this would be the English term for it.

Could be in my case I have a pond shop next door that has them in all regularly used sizes and the internet is littered with them if would like to order it.

Somehow I can't imagine it to be difficult to source in the UK, since it is not the end of the world.

Edit: think I found it...

We’re Irrigation Experts | Advisors And Installers | Plantex UK

The leading supplier of high quality commercial irrigation systems for top fruit and soft fruit growers, vineyards, sports grounds and commercial landscapers.

plantexuk.com

It's indeed a reducing Bush Metric x imperial female thread. 🙂 Thus you would need a piece of pipe with a socket and in this socket the reducing bush instead of a piece of pipe with a cap with a drilled hole etc.

We’re Irrigation Experts | Advisors And Installers | Plantex UK

The leading supplier of high quality commercial irrigation systems for top fruit and soft fruit growers, vineyards, sports grounds and commercial landscapers.

plantexuk.com

We’re Irrigation Experts | Advisors And Installers | Plantex UK

The leading supplier of high quality commercial irrigation systems for top fruit and soft fruit growers, vineyards, sports grounds and commercial landscapers.

plantexuk.com

Thank you for your advice!
I guess now it's too late as I've already put everything together. Tomorrow I'll test it for leaks and hopefully everything's ok.

 

[ScareCrow]

I've been following along as I'll probably do something like this in the future.
I appreciate it's too late now but it just occurred to me, could you use pvc compression fittings at either end of the clear tube and then use washing machine hose tail connectors to give you the connection to your filter pipe? I'm sure I read that you were connecting to the clear pipe with silicone as solvent weld would damage it (can't find it again now), compression fittings would get round that. If I've got that correct, I think that'll be the weakest point.
Your hose connectors are at either end are a lot like bulk head fittings with the nut doing the mechanical holding and the silicone is just acting as a gasket, according to your diagram. So unless you disconnect the unit from the filter a lot I think the silicone will work ok. If the nut becomes lose it'll probably leak. You could add a drop of superglue to the thread where the top of the nut is to help stop the nut working loose.