Heat Pumps & DHW requirements

rayh

Hi all,
What specifications are associated with the requirements of Heat Pump systems for the production of DHW.

AckwelFoley

It can depend.

Is it an Air to water or ground source?

The space heating is the priority of the sizing of the heat pump, there are systems with a back up element of 3 - 6kw to boost water temp when source temp is low, however a correctly sized heap pump should rarely need to use the backup element.

I have a simulation report of the Daiken Altherma air to water that i can upload.. if i knew how to attach a pdf to a post..:o

It basically shows enegy use annualy for 65 degree d hot water and room temp @ 30 degrees

heinbloed

Heatpumps are only efficient (if at all) when long running hours over the entire year can be achieved.If the resulting heat from a heatpump is used for domestic hot water only and that in a standard house hold situation it makes absolutly no economical and enviromental sense to use such an equipment.There might be a different situation if incoming cold water is pre-warmed by a heatpump in an ongoing demand situation, for a swimminghall, hotel, industry. Here a heatpump might work efficient, esp. if some outgoing heat can be used to tap into.But even here the deltaT (which is the difference between the input and output temperature in Kelvin) must be kept low to get an economical benefit from it. So pre-warming fresh water in larger installations-yes.But only prewarming, a few degrees.The rest would have to be topped up by a second heat source, maybe another heatpump in a cascade or just a boiler. For hygene reasons the (potable-)water temperature must have a min. temperature of 65degrees Celsius or so. And a deltaT between a cold medium (like outside air temperature or soil temperature) and the demanded minimum water temperature is very big in our climate. So for sporadical short term usage -like the standard household situation- it makes no sense.

rayh

Thanks Snyper and Heinbloed.

Background to my question – a friend of mine was sold/had installed a Geothermal (ground source) Heat Pump system and when he went to claim his GHS Grant he found that the unit was not registered on SEI list. Most likely did not comply with requirement as set out in http://www.sei.ie/index.asp?locID=772

Following some limited tests on performance, protracted negotiations and adjustments to optimise performance, the installer has now configured the system to produce low temperature DHW (cira. 40 degree C).

What are the options?

heinbloed

Not sure, what do you mean?From the hygenic point a 40 degrees Celsius warm water is critical, esp. if it is stored in larger quantities (more then 150 liters).If the water is of good quality(chlorinated and pressurised to keep the chlorine in it) a quantity of up to 150 liters is considered as being safe- by the plumbing industry.If the DHW water is heated up indirectly, for example by a 40 degrees warm circulation/heatexchanger then the tapped temperature will be less then that.Bringing 10 degrees warm water to 40 degrees demands 30 Kelvin which is high.It might be inefficient.There is a list of test results published where the deltaT can be checked how efficient the heatpump is actually operating when mastering this difference at a certain start temperature(the cold water temperature).Check for this testing lab's web page(they don't sell heatpumps, they only test them and publish the results -only if the manufacturers agree to it. http://www.ntb.ch/2680.html If you can't find the test results there then contact them, they might have test results available but not published yet in their "bulletin".

sinnerboy

http://www.ntb.ch/3896.html

goes direct to the reports

heinbloed

I think one has to pay now for the bulletin which used to be for free, have you done so already ? The latest issue is from 1/2008. But you found the freeway!
Thanks!

rayh

Once again and thanks Heinbloed and Sinnerboy.

Sorry, are these reports available in English?

The unit I refer to is a Lampossa T9 or I do not know the maker of the Heat Pump used.

heinbloed

http://www.lampoassa.fi/en/t_model_technical_details.html

You might be talking about one of these ones.
I have not found any independant report on this type or make. Ask the manufacturer for independant test results.Since it uses the refrigerant R407c this might be the reason why it is not a listed heatpump(climate demaging effect or "CO2 equivalent" of R407c :1 kg of R407c has the same climate demaging effect as 1,500 kg of CO2 !) available for grants, but I realy don't know.
During the manufacturing of a heatpump 2% of the refrigerant are released to the atmosphere, another 3% per year when running it(calculated at a running time of 15 years) and when disposed another 15%. So a heatpump using this refrigerant can't be called "good for the enviroment", why should the taxpayer fork out money for it....?
The efficiency was not mentioned on it's webpage even so this it is a fundamental detail,so it might not be very efficient/competitive. Otherwise they would publish the efficiency rates I'd say.Contact the manufacturer and ask for details, for independant test results according to EN255.

rayh

Thanks very much for your support.

Are the documents on http://www.ntb.ch/3896.html available in English?

sinnerboy

I don't think so

Read here please - and take part !

http://www.boards.ie/vbulletin/showthread.php?t=2055263818

rayh

What is the current and likely future position with the supply of R407c Refrigerants - say for leakage replacements and will disposal become very expensive as Climate Change measures are introduced?

heinbloed

Since HCFCs were banned CFCs were used as a substitute. R407c has only a quarter of the climate demaging potential of the already banned HCFC(Montreal). Since climate protection is on the political agenda I can imagine that the CFCs will follow next. There are now plenty of substitutes available, even neutreal ones like for example CO2 itself. It can be used as a refrigerant and is as climate demaging as - CO2.There are already some heatpumps available using CO2, not many yet though. But the industry is certainly prepared to take the next step without further subsidies and time delays, they have learnt from the past.All it needs is a decision to be made.Recycling of CFCs is already rgulated by various laws. As far as I know there are not many recyclers here in Ireland for CFCs, contact the Dept. of Enviroment for a list and ask them for prices.It's usually the maintenance company(doing the anual check) that has to check the level of refrigerant and to refill the heatpump. This must be protocolled in the anual maintenance report(of which a duplicate must be handed to the owner), existing pressure, min.pressure due to manufacturer's information and topping-up/refilling.This anual check can be expensive, the staff must be trained and certified/legitimised that they're allowed to handle these substances.But this international agreement might have been forgotten by previous gouverments, not been put into Irish legislation.I simply don't know,contact the Dept. of Enviroment.

rayh

Thanks Heinbloed – a very comprehensive outline and I will report response from Dept. of Environment

rayh

Further to my recent post on R407c Refrigerant, I wrote to the Department of the Environment giving some background while asking the following questions;

1.A list of the current licensed Recyclers of refrigerant R407c in Ireland.

2. Current and forecast use of R407c in Ireland.

3. Projected and or likely end use of R407c in Ireland

Received the following reply;

The Greener Homes Scheme is administered by Sustainable Energy Ireland SEI I would advise that you send your query to them at sei.ie. Alternatively you may wish to contact the Department of Communications, Energy and Natural Resources as they are the funding department.

Obviously they did not read my questions or?

heinbloed

No.Contact your local dump, they have a standard list of refrigerator recyclers.These recyclers are licensed by the D.of E. (ahem) and this license states what substances they're allowed to deal with. Check them for the R407c.