EcoRenovator  

Go Back   EcoRenovator > Improvements > Geothermal & Heat Pumps
Advanced Search
 


Blog Register 60+ Home Energy Saving Tips Recent Posts Search Today's Posts Mark Forums Read


Reply
 
Thread Tools Display Modes
Old 02-06-18, 08:18 AM   #1
wrangster
Lurking Renovator
 
Join Date: Feb 2018
Location: Norway
Posts: 7
Thanks: 2
Thanked 0 Times in 0 Posts
Default Diy multi-split - is it possible?

Hi guys, new user from Norway here! I have been reading this great forum for a while, and learned a lot all ready. Right now I am thinking about starting a project of my own.
I live in a boat here in Norway, and the boat has 3 evaporators with fans from an old Cruisair unit. The compressors and condensers are removed by previous owners, but by the wiring diagram it seems to have been 3 different condensing units before. Not shure how many compressors.
I just found a very cheap Fuji heat pump outdoor unit for sale, and I was thinking - is it possible and doable to use those 3 evaporators as the indoor unit for that Fuji. The Fuji is not a multi-split. I do not need individual temperature and fan control for each evaporator, I am ok with them all "doing the same". Am I dreaming too far out here, or could this be a doable project? I have worked 3 years with heat pumps and other cooling equipment earlier, mostly restaurant equipment.

wrangster is offline   Reply With Quote
Old 02-07-18, 11:19 AM   #2
jeff5may
Supreme EcoRenovator
 
Join Date: Jan 2010
Location: elizabethtown, ky, USA
Posts: 2,348
Thanks: 367
Thanked 593 Times in 496 Posts
Send a message via Yahoo to jeff5may
Default

depends on a lot of variables. the most important one is probably the control system. if there is a way to control the outdoor unit, the refrigerant side becomes a matter of plumbing and airflow at each heat exchanger. that is if whatever you have will play well together. Otherwise, something will die!

The more details you provide about the units you have, the better responses you are going to receive. This is a very hands-on DIY oriented forum, with many members who are more than willing to offer advice. Before anything specific can be said, more must be known. The HVAC realm isn't regarded as magical and mysterious for no reason.

Welcome to the forums!

Jeff
jeff5may is offline   Reply With Quote
Old 02-07-18, 04:02 PM   #3
wrangster
Lurking Renovator
 
Join Date: Feb 2018
Location: Norway
Posts: 7
Thanks: 2
Thanked 0 Times in 0 Posts
Default

Thanks for your answer! Yes, I know that the control system will be one of the challenges. I have seen here that some guys are playing with arduino control boards, I have thought maby that could be a route to go. I don't know very much about arduino though.
The thing is that i don't have very much yet. The outdoor unit is something I saw for sale, and the evaporators probably aren't usable since they are 42 years old, and most likely for R12 or R22. The fan motors are probably 115 volt, and I need 220 volt.
But I still wanted to make a tread about diy multi-split, to see if there are others with similar dreams, or just to gather info about this. I can't believe I'm the only one in the world wanting to try turning a single split into a multi-split of some kind. Maby someone allready has tried something similar, and can tell me and others about all the pits not to fall into.
wrangster is offline   Reply With Quote
Old 02-09-18, 07:27 AM   #4
wrangster
Lurking Renovator
 
Join Date: Feb 2018
Location: Norway
Posts: 7
Thanks: 2
Thanked 0 Times in 0 Posts
Default

By googleing a little bit I found that there are branch-boxes available, some with expansion valves. I also found some split pipes meant for adding more indoor units. They all seem to be meant for multi-split outdoor units though, I guess that has to do with the need to control each zone individually.
As I wrote before, in my project I am happy enough with all 3 units acting like one. The small temperature differences I may need, I guess I could achieve only by using manual fan contronls or maby a little bigger evaporator in the "living room" cabin. The boat is a 76 Bertram 46-6 Motoryacht, for those specially interested.
wrangster is offline   Reply With Quote
Old 02-10-18, 04:28 AM   #5
Acuario
Apprentice EcoRenovator
 
Join Date: May 2011
Location: Tortosa, Spain
Posts: 198
Thanks: 2
Thanked 60 Times in 37 Posts
Default

I haven't tried this but here are my thoughts on the project.

From what I have seen there are 2 types of multisplit. The older type (pre inverter) had individual compressors for each circuit and physically shared the evaporator but with each having it's own circuit. The newer inverter types share the compressor and have a splitter to each internal unit. Logically thinking it through this is due to the compressor needing to be powerful enough to supply the maximum output of the unit. On an inverter this can be controlled by speed variation of the compressor. On traditional machines there is no control.

Imagine a multi split with 5 external units and a huge compressor. If only 1 internal unit is in operation the compressor would be seriously overrated in a conventional system if there was a single compressor. With an inverter system the compressor can be regulated so the problem goes away.

So, several things to consider.
- What is the capacity of the exterior unit? Is it sufficient to run the 3 internal units. If it is, is it too big if it is running only 1 unit?
- Are you planning to isolate machines that aren't being run? You will need some form of solenoid shut off valve on each machine to do this.
- You need to make sure there is no possibility the 3 machines are all shut off when the compressor is running. A high pressure switch is a must. This should shut off the compressor if it operates otherwise you may have dangerously high pressures in your system and damage the compressor.

As for the fans and heat exchangers, you can easily get 220-115V transformers and unless the heat exchangers are leaking (check with Nitrogen at high pressure) they may well be useable. The type of gas and its characteristics do make a difference but at the diy/hacker level it's probably not that significant.

Acuario
Acuario is offline   Reply With Quote
The Following User Says Thank You to Acuario For This Useful Post:
stevehull (02-12-18)
Old 02-11-18, 07:27 PM   #6
wrangster
Lurking Renovator
 
Join Date: Feb 2018
Location: Norway
Posts: 7
Thanks: 2
Thanked 0 Times in 0 Posts
Default

Hi Acuario, and thanks for your thougts! The unit I had in mind is an inverter with 4,5 kw max heating capacity. I dont know it's lowest capacity, but I've seen some inverters around 5 kw has lowest from around 600 watts, so I would guess running on one of three evaporators should go just fine.
Thanks for the reminder of solenoids too, I googled "3 evaporators on one compressor" and found some nice explanations on liquid line solenoid valves and thermostatic expansion valves.
So it looks like that part of the project is doable. But I still need to find a way to control the variable speed of the outdoor unit, without the electronics from an indoor unit.
wrangster is offline   Reply With Quote
Old 02-12-18, 01:55 AM   #7
Acuario
Apprentice EcoRenovator
 
Join Date: May 2011
Location: Tortosa, Spain
Posts: 198
Thanks: 2
Thanked 60 Times in 37 Posts
Default

Without the electronics from an indoor unit you will have to build your own controller for the outdoor unit as the chances of breaking the communications protocol with only one end is pretty impossible. Even with the electronics from an indoor unit to allow this it is a challenge - read my thread on controlling a DC inverter machine

With the extra complexity of 3 machines and the need to variably control the output to balance across the 3 you have a big challenge.

ThMihov is tackling the use of an inverter machine in his project My DIY heatpump attempt but has the internal unit electronics to hack with an IR Blaster rather than attempting to replicate the control system.

Have a good read and search for BLDC motor control circuits as this is what you will need for the external unit.

Good luck if you decide to proceed and keep us posted!

Acuario
Acuario is offline   Reply With Quote
Old 02-12-18, 12:50 PM   #8
jeff5may
Supreme EcoRenovator
 
Join Date: Jan 2010
Location: elizabethtown, ky, USA
Posts: 2,348
Thanks: 367
Thanked 593 Times in 496 Posts
Send a message via Yahoo to jeff5may
Default

There are standalone control boards for doing what you want to with what have you. I have found that it is a lot easier to replace the control box than to assume control of it. The stuff I have been using is qunda brand. They also make remote controls for the consumer aftermarket and other digital controller modules than just for heat pumps.

I have seen they make an inverter compressor control, but I've never had or rigged one up. The magical machines I have built have all been constant speed.
jeff5may is offline   Reply With Quote
Old 02-15-18, 05:17 PM   #9
wrangster
Lurking Renovator
 
Join Date: Feb 2018
Location: Norway
Posts: 7
Thanks: 2
Thanked 0 Times in 0 Posts
Default

I decided to take the boring route for now, and bought another used ashp complete. I asked my old boss about diy multisplit, and he just shook his head. He is one of the hvac guys for shure. He said that that I would be very lucky just to make 3 fans work as one, and even if I did I would never be able to match the effect that an original indoor unit would give.
I also asked him about making something else out of my 3 evaporators, but he wasn't very positive to that either. He said its no problem to make one machine run 3 evaporators, but again the effect would be nothing like an ashp. "Like a refrigerator using 1 kw doesn't give out 3 or 4 kw of heat in the rear. The computer part of a heat pump is what makes it effective, and they are sometimes very delicate. Cards can be broken just by trying things they are not made for, like other or broken fans."
He said if I absolutely wanted to make something of my own, I should take use of the seawater around me and make somthing water to water.

Jeff5may, I think I found something like what you are mentioning here:
wrangster is offline   Reply With Quote
Old 02-16-18, 10:24 PM   #10
jeff5may
Supreme EcoRenovator
 
Join Date: Jan 2010
Location: elizabethtown, ky, USA
Posts: 2,348
Thanks: 367
Thanked 593 Times in 496 Posts
Send a message via Yahoo to jeff5may
Default

Yup, same brand and general purpose rig. That one is more basic than the one I bought. It only does air conditioning and has room air defrost. It would work for cooling though.

The model number of the rig I bought is QD-U12A. It controls a reversing valve, so it will do both heating and cooling. It has indoor fan defrost in cooling and reverse cycle defrost in heating. I am very happy with the controller. It just works like it should. I bought it on Amazon for around 40 US dollars shipped.

https://www.amazon.com/Universal-Con.../dp/B00TLXA8TK

jeff5may is offline   Reply With Quote
Reply


Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -5. The time now is 05:46 PM.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2020, vBulletin Solutions Inc.
Ad Management by RedTyger
Inactive Reminders By Icora Web Design