Using small Window A/C for DHW Heater - Page 2

geoheatnz · 03-06-12, 01:25 AM

Hi there ,
to get maximum efficency from your heatpump you need to keep your approach temp low , this is the temp difference between water out of heat exchanger (hx) and the condensing temp or high pressure converted to temp on p/t chart.
The best way to do this is have as much water flow through hx as possible and to have supply from bottom of cylinder and the return to bottom as well if possible , this also gives you a small temp difference between supply and return temps and does not effect stratification of water as much as circulating from the top down.
It is also best to have counter flow like you indicated with refrigerant flow and water , also have discharge at top and liquid out the bottom of hx.

Hope this helps some.

cheers Andy

Xringer · 03-07-12, 07:56 AM

I was thinking of using a differential controller to turn on the pump,
whenever the HX is warmer than the stored water in the boiler.

I don't understand why you would want to preserve stratification of the stored water.
In any event, my boiler's water jacket is not like a cylindrical tank and the turbulence
in the stored water is going to be pretty high when the pump turns on,
even if the input and output were both on the bottom of the boiler.

The recirculate water (76 gallons) is stored in the water-jacket that surrounds the fire-boxes.
The only slightly large volume area is where the copper DHW HX coil sits.
Stratification does occur, but it's easily disrupted whenever HW is used,
or if one of the circulator pumps came on (in case of a call for heat).

Since I already have a pump installed (for basement heat), which I never use,

Perhaps just tapping into the pump relay with my controller,
and diverting it's water flow to my HX will be easier (and cheaper)
than adding a third pump to the mix..?.

Using hose-type shut-offs (on Tees) and a valves to shut off the basement loop,
would allow the basement pump to feed into any kind of heating unit I wanted to install,
Using washing machine hoses.. (Insulated of course).

geoheatnz · 03-08-12, 12:44 AM

Hi X ringer,
your boiler sure is a lot different than anything we get in NZ! Is that where your hot water is stored or does this heat your house as well ? or do you have a cylinder some where .
If you were to build something like the geyser that would be the best solution for year round hot water and hooked up to a pre heat tank where it can be most efficent , get heat given off by the boiller in winter , dehumidify basement year round.
cheers Andy

Xringer · 03-08-12, 06:33 AM

Yeah, it's the middle sized model HS Tarm, holding 76 gallons in the water-jacket.
We burn 1/2 gallon of oil every morning.

If I can successfully add heat to that 76 gallons of storage, using a small ASHP,
I might be able to turn off the oil burner during warm weather..

We only dehumidify the basement during the summer,
since it's drier down there during the winter. (and colder too).

I don't know if using a DIY geyser-clone in my cold basement would be practical during the colder months.
Just have to try it out and see if it works.

Xringer · 03-30-12, 10:58 AM

Quote:

Originally Posted by AC_Hacker

Maybe your router speed controller?

-AC

The little lathe has been repaired..

And the drill-mill is still working..

But, I have a bunch of plumbing to get done before any hobby stuff gets done..

stuart1648 · 04-05-12, 12:04 AM

heres an idea for a project:turn a window ac into a window ac/heatpump by messing around with ducts rather than valves.Ie..in the normal ac mode ducts stay same but in heatpump mode ducts reverse the airflows.

Xringer · 04-05-12, 08:12 AM

That works. Easy to do, but the results are less than spectacular.
http://i46.photobucket.com/albums/f1.../NCL/setup.jpg
http://i46.photobucket.com/albums/f1...L/outdoors.jpg
http://i46.photobucket.com/albums/f1.../NCL/90deg.jpg

The outdoor temp (being cool in winter) will keep shutting it off.

You just need to move the temp sensor on the indoor coil, to the outdoor coil (heat out).
That would trick the control into thinking it was really hot indoors and
make the motors run.

stuart1648 · 04-05-12, 09:33 AM

That would involve moving the ac around and attendant hassles as you say;I meant leaving things be but merely redirecting airflows via low -tech ductwork ;ie..inside air is redirected out and vice versa;the temp control would just be used backwards

AC_Hacker · 04-05-12, 09:36 AM

Quote:

Originally Posted by stuart1648

That would involve moving the ac around and attendant hassles as you say;I meant leaving things be but merely redirecting airflows via low -tech ductwork ;ie..inside air is redirected out and vice versa;the temp control would just be used backwards

You really won't know until you try it.

-AC

Xringer · 04-05-12, 10:29 AM

Quote:

Originally Posted by stuart1648

That would involve moving the ac around and attendant hassles as you say;I meant leaving things be but merely redirecting airflows via low -tech ductwork ;ie..inside air is redirected out and vice versa;the temp control would just be used backwards

Take a look at the locations of the coils. What you suggest would be way more trouble than just reversing the unit.

However, if a manufacturer built a wall-shaker with two enclosed HXs,
with their air inputs and outputs controlled by gates, to switch functions..
That could work, but the AC would be much larger and costlier.

03-07-12, 07:56 AM	#12
Xringer Lex Parsimoniae Join Date: Feb 2009 Location: Woburn, MA Posts: 4,918 Thanks: 114 Thanked 250 Times in 230 Posts	I was thinking of using a differential controller to turn on the pump, whenever the HX is warmer than the stored water in the boiler. I don't understand why you would want to preserve stratification of the stored water. In any event, my boiler's water jacket is not like a cylindrical tank and the turbulence in the stored water is going to be pretty high when the pump turns on, even if the input and output were both on the bottom of the boiler. The recirculate water (76 gallons) is stored in the water-jacket that surrounds the fire-boxes. The only slightly large volume area is where the copper DHW HX coil sits. Stratification does occur, but it's easily disrupted whenever HW is used, or if one of the circulator pumps came on (in case of a call for heat). Since I already have a pump installed (for basement heat), which I never use, Perhaps just tapping into the pump relay with my controller, and diverting it's water flow to my HX will be easier (and cheaper) than adding a third pump to the mix..?. Using hose-type shut-offs (on Tees) and a valves to shut off the basement loop, would allow the basement pump to feed into any kind of heating unit I wanted to install, Using washing machine hoses.. (Insulated of course). __________________ My hobby is installing & trying to repair mini-splits EPA 608 Type 1 Technician Certification ~ 5 lbs or less..

03-08-12, 06:33 AM	#14
Xringer Lex Parsimoniae Join Date: Feb 2009 Location: Woburn, MA Posts: 4,918 Thanks: 114 Thanked 250 Times in 230 Posts	Yeah, it's the middle sized model HS Tarm, holding 76 gallons in the water-jacket. We burn 1/2 gallon of oil every morning. If I can successfully add heat to that 76 gallons of storage, using a small ASHP, I might be able to turn off the oil burner during warm weather.. We only dehumidify the basement during the summer, since it's drier down there during the winter. (and colder too). I don't know if using a DIY geyser-clone in my cold basement would be practical during the colder months. Just have to try it out and see if it works. __________________ My hobby is installing & trying to repair mini-splits EPA 608 Type 1 Technician Certification ~ 5 lbs or less..

04-05-12, 08:12 AM	#17
Xringer Lex Parsimoniae Join Date: Feb 2009 Location: Woburn, MA Posts: 4,918 Thanks: 114 Thanked 250 Times in 230 Posts	Install it backwards? That works. Easy to do, but the results are less than spectacular. http://i46.photobucket.com/albums/f1.../NCL/setup.jpg http://i46.photobucket.com/albums/f1...L/outdoors.jpg http://i46.photobucket.com/albums/f1.../NCL/90deg.jpg The outdoor temp (being cool in winter) will keep shutting it off. You just need to move the temp sensor on the indoor coil, to the outdoor coil (heat out). That would trick the control into thinking it was really hot indoors and make the motors run. __________________ My hobby is installing & trying to repair mini-splits EPA 608 Type 1 Technician Certification ~ 5 lbs or less..

04-05-12, 09:33 AM	#18
stuart1648 Lurking Renovator Join Date: Apr 2012 Location: longview wa Posts: 18 Thanks: 0 Thanked 0 Times in 0 Posts	reverse the ac That would involve moving the ac around and attendant hassles as you say;I meant leaving things be but merely redirecting airflows via low -tech ductwork ;ie..inside air is redirected out and vice versa;the temp control would just be used backwards

03-06-12, 01:25 AM	#11
geoheatnz Lurking Renovator Join Date: Jul 2011 Location: feilding , n.z Posts: 27 Thanks: 4 Thanked 8 Times in 5 Posts	Hi there , to get maximum efficency from your heatpump you need to keep your approach temp low , this is the temp difference between water out of heat exchanger (hx) and the condensing temp or high pressure converted to temp on p/t chart. The best way to do this is have as much water flow through hx as possible and to have supply from bottom of cylinder and the return to bottom as well if possible , this also gives you a small temp difference between supply and return temps and does not effect stratification of water as much as circulating from the top down. It is also best to have counter flow like you indicated with refrigerant flow and water , also have discharge at top and liquid out the bottom of hx. Hope this helps some. cheers Andy

03-08-12, 12:44 AM	#13
geoheatnz Lurking Renovator Join Date: Jul 2011 Location: feilding , n.z Posts: 27 Thanks: 4 Thanked 8 Times in 5 Posts	Hi X ringer, your boiler sure is a lot different than anything we get in NZ! Is that where your hot water is stored or does this heat your house as well ? or do you have a cylinder some where . If you were to build something like the geyser that would be the best solution for year round hot water and hooked up to a pre heat tank where it can be most efficent , get heat given off by the boiller in winter , dehumidify basement year round. cheers Andy

04-05-12, 12:04 AM	#16
stuart1648 Lurking Renovator Join Date: Apr 2012 Location: longview wa Posts: 18 Thanks: 0 Thanked 0 Times in 0 Posts	heres an idea for a project:turn a window ac into a window ac/heatpump by messing around with ducts rather than valves.Ie..in the normal ac mode ducts stay same but in heatpump mode ducts reverse the airflows.