HPWH issue

[Lc_shi]

hot water is becoming more essential for each family in our country. There are type of gas\resistance\solar energy water heater,now the HPWH(heat pump water heater) come into the field in the name of saving energy. I want to listen your comments on this? is it energy efficient for HPWh? is there any problems with it?

rgds
lichuan

[techguy]

HI L
Sanyo do a gas engine heatpump for the domestic market which is only available in Asia. But if you have a need for cooling in summer it will give you free hot water all summer.@75C
I have worked on various ground /water ,air source heat pumps and have yet to come accross one i would recommend the technology is relativly good but the water temp is always to low and a back up electric hater is always required, the most efficent ones i've worked on are the water source type
I believe there are some CO'2 heatpumps available but have yet to see one so I can't comment
Hope this helps
T

[botrous]

I don't think HPWh (what ever it is ) is more efficient than solar panels water heaters . . . as techguy said , if you need cooling in summer , you can get free hot water from your system by using the heat rejected by the condenser . . .
But making a heat pump specially to warm water , . . . i donno , i have to see more about that subject as well i don't really understand what u r talking about . . . several type of systems are called heat pump such as geothermal heat pump etc ... so what are you talking about ??? so i can have a look on the subject and learn

[frank]

Sanyo do a gas engine heatpump for the domestic market which is only available in Asia.

Hi techguy

I think that you will find the Sanyo gas engine heat pump is now available in the UK as demonstrated at the recent RAC show in Birmingham (February 2005)

[wambat]

Here is a pretty god article http://www.aceee.org/buildings/coml_...attach-plr.pdf

[Temprite]

I don't think HPWh (what ever it is ) is more efficient than solar panels water heaters . . . as techguy said , if you need cooling in summer , you can get free hot water from your system by using the heat rejected by the condenser . . .
But making a heat pump specially to warm water , . . . i donno , i have to see more about that subject as well i don't really understand what u r talking about . . . several type of systems are called heat pump such as geothermal heat pump etc ... so what are you talking about ??? so i can have a look on the subject and learn

Hello Botrous

Check this out.
www.enviro-friendly.com/quantum-faqs.shtml

[frank]

http://www.buildingdesign.co.uk/mech/sanyo/

[MichaelSiddons]

A new Patent that can improve the operating efficiency of heat pump water heaters has been developed. Energy savings above 75% have been recorded at night!

The Patent design in question relates to what is called a condenser/tank. The condenser/tank has been designed to connect to air conditioning units.

We have been field trailing 340 litre condenser/tanks connected to air conditioners with a 1.3 kW compressors and the results are extremely impressive. As Len Taylor says concerning his own test results:

“This is really an excellent performance for an air source heat-pump of this capacity on such a cold day and would facilitate efficient operation with almost any combination of on-demand or off-peak modes...Examples: ambient 8C to 10C, run time 3hrs 36 mins, C.O.P 2.98; ambient 16C, run time 2hrs 2mins, C.O.P 4.80; and so on.” L.E. Taylor M.Eng Sc: CPEng. August 2005

The water heater operates at night to take advantage of cheap off-peak electrical power. Because it heats up in two to three hours, on off-peak power and the heater does not use heating elements, hot water costs are also 75% cheaper than conventional hot water heating costs.

The only other product like it is the Quantum Energy System and this new condenser/tank heat pump water heaters far exceeds the performance of the Quantum.

[Peter_1]

HI L
.....and have yet to come accross one i would recommend the technology is relativly good but the water temp is always to low and a back up electric hater is always required, the most efficent ones i've worked on are the water source type

We use in our country often radiant heating, so you don't need that high temperatures for this kind of heating, 30° to 35°C.
If you need to warm it yup to an average of 32°C, then you can condense at +/-38°C and if you can use a DX coil in the ground, then you can evaporate at 7°C (for an average soil temperature of 12°C we have here)
This gives COP's of far more then 5!

Michael, saying that you can reduce the electricity bill with 75% during the night says nothing: we don't know the price for a kWh during night compared to that of that of the day.
And apparently, you're not the first; Wambat or Temprite gave us a link where they speak also of a 75% reduction.
I'm always skeptic when someone says - I'm not saying you're wrong - invented something that can reduce their actual bills with more then 5 to 10%.

If Danfoss say that there AKV's can reduce the bill with 20 to 30%, then I don't believe this because they can't prove this.

I've said it already many times in this forum, the biggest savings can only be made the more you approach the ideal thermodynamic Carnot cycle or in other words,...trying to evaporate as high as possible and to condense as low as possible.

[MichaelSiddons]

The Solarstream has a long life design exceptional efficieny, (because it is a direct heat transfer design) and an improvement on our old design the Quantum water heater. PS I developed the Quantum air sourced HPWH.

Direct Heat Transfer means water is heated without a vented heat exchanger. Heat transfers direct through metal without a void. The Condenser-tank configuration is the only type of HPWH which has this design advantage when used to heat potable hot water. See the Siddonssolarstream web site fro deatils.

The new Siddons Solarstream www.siddonssolarstream.com is more enrgy efficient than solar water heaters especially when water useage by a family is more tha 200 litres a day.

Regards,

Mike

[techguy]

Hi Frank,

The commercial unit is available from 22 kw upward I suppose you could use this in a domestic situation but the cost of the plant would be very expensive. it is a great system but not cheap. We have installed a few in the uk in "homes" but these where all 6 million pound plus homes not your commom 3 bedroom semis.


Regards

T

[NoNickName]

I think ground source or water/water heat pumps are still the most efficient and economical. Gas is expensive and reducing availabilities are pending. Air can be cold in places, so air/water heat pumps is not efficient enough
Ground is free, and process or non-drinkable water (sea water) is generally available in most parts of the world.
New compressors with vapor injection can achieve high water temperatures and high COPs

[Peter_1]

New compressors with vapor injection can achieve high water temperatures and high COPs

What compressors and what gasses are you thinking on?

[US Iceman]

...vapor injection...

Is this the same as an economizer cycle??

[NoNickName]

Copeland models ZH, specifically designed for high temperature water heating

[Peter_1]

What about a small NH3 compressor with is high COP but especially it's relative very high discharge temperatures?

[NoNickName]

You can't have NH3 in domestic appliances

[Peter_1]

Oh, and why not then?
What about the small absorption fridges then?
What about the domestic fridges filled with propane
There could be a great advantage using NH3.

[NoNickName]

Propane is non toxic. Nh3 is.
Absorption fridges I know about are running burning methane.

[Peter_1]

Nobody said you have to breath it,
machine can be installed outdoors,
NH3 is widely used in food processing, direct via pumping in the coils,
propane is highly flammable and explosive,
most domestic fridges I know work on an ammonia solution

That's your vision, that's not the law I suppose, at least not in Belgium,
I was speaking about ..if you should install NH3...what about COP and temperatures.

[Josip]

Propane is non toxic. Nh3 is.
Absorption fridges I know about are running burning methane.

Hello,

In good old days there was a domestic fridge absorbtion type with ammonia and only electric heater.

Need only sometimes to turn it upside-down to mix the liquids inside

something more about at:
http://techref.massmind.org/techref/other/spac.htm

under: crazy idea

Best regrds,

Josip

[US Iceman]

In good old days there was a domestic fridge absorption type with ammonia and only electric heater.

Need only sometimes to turn it upside-down to mix the liquids inside

Sounds like the old brown box Servel absorbers (also Arkla-Servel depending on the date).

Some of these also had a gas burner I believe.

[NoNickName]

For peter_1: for household appliance I meant something to be installed in the house. Of course, if the plant is remote, or in an appropriate technical room, there's no problem with ammonia.
It's true I don't have to smell it, but safety is preventive, not protective. So everybody should take care of something that could happen, not something that is not supposed to.
I don't know what could be the COP and performance. I'm afraid it is difficult to find appropriate small compressors for small capacities and NH3, but I really don't know. We are not dealing with ammonia.

[Josip]

For peter_1: for household appliance I meant something to be installed in the house. Of course, if the plant is remote, or in an appropriate technical room, there's no problem with ammonia.
It's true I don't have to smell it, but safety is preventive, not protective. So everybody should take care of something that could happen, not something that is not supposed to.
I don't know what could be the COP and performance. I'm afraid it is difficult to find appropriate small compressors for small capacities and NH3, but I really don't know. We are not dealing with ammonia.

Hello,

almost everything is possible to make and to install, but many yeras ago for some good and bad reasons someone devided refrigeration to household and industrial.

Today we have industrial side using ammonia and other dangerous refrigerants and household appliancess using nondangerous nature and user friendly *****s.

I do not believe that any COP can change this

I believe you agree with me

Each industry is huge and money dictates COP

Best regards,

[NoNickName]

Today I received a phone call for a belgian who wanted a GHP with water leaving 62° and refrigerant R410.
Assuming a Tc +5K from leaving water temperature, that would result in a condensing pressure of 40bar.
Now: who in the world would like to have such a bomb in his/her house?
How much does a PHE with certified service pressure of 50 bars cost?
What compressor do I use?

this is pure madness...

[Steve Wright]

In the Uninted States we can have NH3 in appliances, I'm not sure but I think Canada can too.

The gas fired fridges have NH3 as a refrigerant.

Steve

[Peter_1]

We have heat reclaim systems running - posted already pictures on this forum - on R22 and at a pressure of +/- 15 bar with water temperatures of +/- 70°C.

So, you can calculate it in such a way that you use the discharge temperatures for the higher range temperatures and remain acceptable low in HP.

A manufacturer told me they build some months ago a pack with 2 Plate HE: 1 for condensing almoste completely the discharge and preheating the water and a second to increase the already preheated water with the discharge temperature.
I never saw it this way. What do others think?

NH3 gives with a COP of 5.3 (5°CTV/35TC) discharge temperatures of +/-90°C.

NoNickName, strange I had yesterday almost exactly the same question. But they needed that high temperature because they want to replace the old oil burner which heated the old the heating panels which were once designed for 65°C/55°C.

They had heard that a HP was so economic.

I advised them that they better looked for a new high efficient oil burner or if they want to instal a HP, that they need to modify much more then just the burner.

[US Iceman]

A manufacturer told me they build some months ago a pack with 2 Plate HE: 1 for condensing almost completely the discharge and preheating the water and a second to increase the already preheated water with the discharge temperature.
I never saw it this way. What do others think?

I think this is the best way to recover heat. When recovering heat from a refrigeration system we have two things to consider.

1) Temperature (actual discharge temperature available which is greater than the condensing temperature)
2) Heat Energy (refrigerant condensing)

If you use two heat exchangers in series, the first one will warm the water up as much as possible. The phase change of the refrigerant provides a lot of energy for heating, but not very much temperature.

The second heat exchanger takes the slightly warm water and now uses the discharge temperature of the refrigerant to provide the higher temperature.

Of course you want the water flow to be counter-flow to the refrigerant flow for greatest heating effect.

Depending on the water heating requirements and heat available from the refrigeration system you may not have to run a very high discharge pressure.

The way I think of this follows: Find the best discharge pressure to provide a good COP. Then; is the discharge temperature of the refrigerant "hot enough" to provide the final temperature needed?

If there is a cooling process where you can extract heat and then you use a heat pump to increase the temperature, the COP of the heat pump can increase very high since both the cooling and heating are useful.

[NoNickName]

For Peter: the question arises from advertising from Copeland and some GHP producers, like Robur, who claim and actually do high water temperature heating with gas burning-aided HP.

For US_Iceman: I don't think it's a matter of technology, but more about convenience. An industry like ours would only consider to build HPs only if:
1) price would be reasonable
2) market share would be reasonable

High COP HPs with such refined components would go against 1) .
If consultants do not convince customer of the usefulness of such devices, then we face a situation were we go against 2).

Standard COP, low temperature, low price equipment for the big market is still winning. Nobody wants to be Don Quixote against the windmills.

[Josip]

Hello guys,

Agree with each of you....

I told you about COP in my post above.

We have to make that what they ask for and not what is better

Best regards

Josip

[Bulldog67]

Hello everyone, "newby onboard". Just catching on to whats being discussed. Noticed a reference in Peters message referencing ground temperature. Do you have a geothermal sytem installed in your home? Do you find it to be a viable energy saving system? I am interested in this technology and would appreciate
your viewpoint.

[US Iceman]

Peter, Josip, & NoNickName,

I agree with all of the comments. The equipment types are driven by the markets served. If the customer only wants GSHP's that is what they buy.

And as NoNickkName said, if someone does not show the customer or user the differences and/or benefits of alternative technology the new systems will not be sold for 20 years.

Especially if energy stays cheap. If energy gets really expensive things could change quickly.

I don't work with the residential or commercial markets, so the industrial customers are a little more receptive to new ideas. However, there is still a lot of resistance to new technology that falls under the "Not Invented Here Syndrome" or "Who else has one".

If you guys see what I mean???

[NoNickName]

Also, inside I feel resistance for the "we are not market leaders" syndrome. Good ideas usually go unnoticed or discarded at all because of this.

I second US_Iceman completely.