Hybrid home energy distribution

I don't think it would be too much of a hassle.

My family once bought a house that had a small steel water tank on the roof. If we happened to take a bath late in the morning, we could have a hot shower. We didn't have a dishwasher but we used the hot water to wash the dishes. Sorry for the laundry because my mom didn't believe that hot water was good for the clothes.

Right now, I'm saving up to buy my own house. I was thinking of doing the same thing except that I'll have some water that doesn't get heated.

Water supply to washing machine could be rerouted through the heater/supply (I'm assuming wash water to be less than 60 celsius). You may need to change the hose grade though.

Also, if one analyse final energy conversion in a typical home, it's either mechanical or heat(inject/extract). As posted elsewhere in CR4 the Amish community is using pneumatic motors to run their washing machines!

Title is a good one,Gwen.

Gwen,

Small savings will help.

I remember fixing washing machines made in the 50s and 60s which had heaters in them. More recently we see less of them as cold water detergent is popular in Australia.

I'd have to agree that heating water in the appliance itself is a poor way to go. As an example, our dishwasher didn't work well from new until I finally got around to getting rid of the instantaneous gas hot water system and replaced it with a Rheem heatpump unit. Now the hot water is at 75c instead of 45c (when it didn't blow out) and the dishwasher has worked perfectly since.

The heatpump costs us less than 10% as much as the gas monster did. Our total energy bill fell and we no longer cop cold showers. The heatpump costs about 7c per kwh and returns 3.25kw of heat for each kw bought. The LPG costs about 50% more per litre than unleaded petrol and ulp is 50% tax in Australia.

In our warm humid climate I even use the "waste cold" to dehumidify the air under the house.

Hi Emjay4119,

I am interested in the heat pump system for heating water that you referred to. We currently use a system that heats 360 l of water using off peak power that costs about 4.67 ¢Kwh^-1. It has a serious draw back though as when you use all the hot water you need to wait overnight before you have any more. Recently it burnt out the element and as there is no way to know that it hasn't heated the water overnight we didn't realize till later the next day. The delay in finding the problem meant waiting till the next day for somebody to arrive followed by a day diagnosing the problem and a further day to fix it meaning no hot water for three days. Not being able to have a shower for three days in Sydney during summer is something I would prefer to avoid. At any rate the system is on its last legs and is likely to give out completely in the not too distant future. If you have a link to somewhere that has information on the heat pump system you referred to it would be greatly appreciated.

Gewn,

There seam to be big differences on appliance water connections through the world. The dual hot/cold system is an interesting system. Is it available with many suppliers? Can you give some makes and models?

Certainly in Australia it is the norm for washing machines to have connections for both hot and cold water and most houses have both plumbed to supply hot and cold water to them. As Emjay4119 said there were some machines that had elements in them but I havn't seen one for a long time now. Here are some or the common washing machines available in Australia and to the best of my knowledge they all have hot and cold water connections The quality of the machine governs the degree of control over the water temperature but the minimum is hot, cold and a mixture of the two giving warm water. I believe the more expensive models have the ability to vary the temperature on demand by adjusting the mixing ratio but this is not my field and I can't confirm this.

Dish washers need to heat the water to 100° C for the final rinse and so by using hot water you will not be able to get rid of the heating element. If you do use hot water you in a dishwasher you will reduce the amount of power used by about 1 Kwh per load so the savings are not that great. If you had solar hot water available it might be worth it but anything else isn't going to make that much difference.

I think there is some confusion between heat pumps and instantaneous systems. The heat pumps produce water at 75° C so there is no problem about bacteria when storing it. The instantaneous systems that have outputs less than 60° C don't store the water. These systems only heat the water as it is used and only while the water is flowing. They do not start heating the water until they detect the flow of water and then shut down as soon as you turn the tap off again. The only advantage is that they only heat the water on demand so any loss is minimized but they have many disadvantages and are not the most reliable methods of heating water.

Masu,

The hot and cold water connection system is interesting but not existing in this part of the world. Strange.

What I mean is a connection to the central heating system, where the heating fluid is circulated to heat the washing water. When you use hot tap water, the first part of cold water is already in your machine, which is specially designed to use as less water as possible.

You have loaded 10l of water in the machine, 5 were cold, 5 hot. But you have paid for 10l hot water. Still you need to heat the water to have the temp in the machine that you want. And the hot water in the pipes is cooling down again. The longer the distance the more losses you have.

With a circulation system you take heat till the machine has its temperature.

It is a bit uninteresting in warm climates, as you don't need to heat your house. (you need to cool it) I don need to heat approx 8 months/year. The lost energy of the cooling down of the pipes goes into the house. In fact it is no loss. (it helps drying the dog)

When you have an alternative system to generate hot water the more you use it, the more benefit it has.

A little question: why don't you heat your tank with a solar collector, Sydney must have enough direct solar heat (not yesterday, I saw the thunderstorms on TV). With 6 adults that take a shower each day the solar collector is easily paid back.

An electric feed through instantaneous heater can help you cope with the bad weather days and when you ran out of heat.

Try to redo your calculation with the power used for water heating purposes and go hybrid.

Gwen

A little question: why don't you heat your tank with a solar collector, Sydney must have enough direct solar heat (not yesterday, I saw the thunderstorms on TV). With 6 adults that take a shower each day the solar collector is easily paid back.

That may very well be the way to go. Up until now the cost of solar hot water systems has been prohibitively expensive. Another factor is that if you heat the water up during periods of low electricity demand you can purchase the electricity at a discount of around 70% thus reducing the running costs considerably.

As a result solar hot water hasn't been that cost effective however with the introduction of subsidies for installing solar system and the increasing cost of electricity it is definitely worth a serious look.

The current system we have needs replacing soon and I am about to go through the process of working out what is the best solution for us. When I do go through the process I will start a thread on my blog that has all the relevant information that and the process behind selecting whatever the final solution turns out to be.

Do you think a thread like this would be helpful to others?

It is helpfully as it shows the different pitfalls that need to be taken care of.

You must see this as a brainstorm - FMEA session.

And it is more interesting than those threads that need to solve homework problems.

I'm seriously thinking on starting an own business in alternative energy supply for home use. I discover that things are quite different all over the world and this part of the world really needs to wake up.

The rising oil prices are beneficial: people are interested in it.

Gwen,

A friend and former work colleague here in Mackay runs an alternative energy business as a side line. It is very interesting, if you do it I hope you go well.

Solar energy for pumping water on acreage blocks is becoming more prevalent here due to cost competitiveness with installing submains and control gear.

Masu this may help.

http://www.rheem.com.au/domestic_product.asp?model=551275&cat_id= - sorry, link no longer available

I did the sums for solar close coupled hot water. I even added bracing to my roof in anticipation, then realised the payback period was longer than the life I'd seem many units achieve. I removed a unit for a bloke as a favour and was considering refurbishing it until I realised just how bad it was.

The latest heat pump units have a COP of over 4 using 400 series gasses and I'm told scroll compressors. Mine uses R22 and a rotary for a COP of 3.25.

The only complaint I have with mine is the type of thermostat that they use is a cheap thing which failed and Rheem didn't cover it on warranty, and because the local bloke tried to get warranty for me it cost me one service call too. I promptly ordered a spare as the thing has oddball fixing centres. The new ones mount the thermostat differently, but it would pay to check that a standard Klixon or Robertshaw will fit. Mine uses a Derwent which is such an oddity it isn't listed.

Thanks for the link, it's a great help.

Emjay4119,

I just checked out that website you gave and got this message:

Sorry, the requested product is currently unavailable. Please choose another product.

First time I saw a negative comment get quick results .

http://www.rheem.com.au/

This is the home page the menu should get you there.

This would seem to be the nearest to what I have:

http://www.appliancesonline.com.au/Merchant2/

merchant.mvc?Screen=PROD&Store_Code=appliances_online&Product_Code=W502

(you would need to re-connect the two halves of the link)

Very economical, and produced using cast iron to stabilise the load, rather than the usual here in UK - a lump of concrete sat on top the drum. Much quieter on spin. Previous machine shook itself to death after less than 3 years, the Miele has not had any problems in 5. (at least 3-4 loads per day)

Here in England most washing machines and some dishwashers have hot and cold fill so that you can use some hot water from the house oil / gas system.

I am tempted to look at a heat pump ground source system - our sunshine is too rare for solar - for hot water and heating of the house, however, I understand that the output temperature here would be around 45 degrees Celcius. This is a very risky temperature to store water as it is the fastest growth rate for some of the most unpleasant bugs - hence our problems in aircon systems in summer where airborne diseases have affected ( and killed) people on several occasions.

Who has any solution to this problem.

There seam to be big differences on appliance water connections through the world. The dual hot/cold system is an interesting system. Is it available with many suppliers? Can you give some makes and models?

I once connected the water intake to the hot water supply, it did not function well as the machine needs cold water also. It is only in some parts of the cycle that it needs heat. (the drying cycle needs cold water to cool the hot water damp and this way the plates are dried)

You need to store the hot water at at least 60°C to prevent the formation of bacteria, going above 70°C starts to kill them. You can work in a dual stage cycle: the first tank heats the water to 45°C with the heat pump output. A second boiler is fed with this water and heated to >75°C with gas.

Another option is to look into a higher condensation pressure, it could drive the price of the pump up and take the efficacy down.

The exhaust of the pump will be higher than 45°C, this is what the final pressure limits. What you can do is guide this gas through the hot boiler, where it can give the excess heat and let it condensate in the colder boiler. The 45°C water can be used in a Hydronic floor heating. The hot gasses will not be able to heat your complete domestic water but it is certainly better than going for complete electrical heating. (the two stage system is widely used in the industry)

Don't use the water in the 45°C tank directly but create a heat exchanger in the form of a spiralled pipe in the water tank, the amount of water in the pip is low, the speeds are acceptable and you can clean it, if you want, with a pig. Improving the water quality.

Gwen

In the UK most washing machines - we use front loading automatics - have both hot and cold fill. If you select the hotter washes the machine will hot fill, if you select a cooler programme the unit will cold fill and then electrically heat the water up to target. Really these days, it should be possible to measure the water at the intake and mix to match the target temperature.

On the heat pump issue, my concern is that the heat pump will be able to take energy from the ground source all the time to take it up to 45 degrees C, That will give a large volume of water at 45 degrees which is a health issue. The draw off of hot water for showers etc is all in the morning, so the oil boiler would need to be in action for one hour at high temperature outputs, the other 23 hours we have a large tank of tepid water!

Any solutions?

Hugh Mattos

Are you serious: the incoming water is 40°C?

Is the pipe buried?

Is this water potable?

We have a certain amount of pipe coming into my house that is above ground and is exposed to sunlight. During summer if the water is allowed to stand in the pipes for any length of time it can heat up considerably. I have seen the cold water heat up to well above 50° C and have been burnt on at least one occasion that I can remember. One of the things you end up instinctively doing is checking the temperature of the cold water before you use it. Normally once you have flushed the pipes it cools back down to a sort of normal temperature. Even so during summer15-20° C is around the sort of temperature to expect for the cold water even from underground pipes. I havn't bothered to check the sort of temperatures during winter but I am pretty sure that it doesn't go too much below about 15° C. Water freezing in pipes is unknown in any of the major population centers and pretty much unheard of in the rest of the continent. Parts of the highland in the SE corner and places in the desert get below zero at night during winter and I have heard of pipes freezing there but it is rare on the mainland. Tasmania is somewhat colder than the mainland and it could be a problem there but I cant confirm it as all whenever I have been in Tasmania I have always stayed in hotels.

Pipes frequently freeze in Deloraine TAS and in 1964 we had trouble with burst pipes on the Atherton Tableland though the effects of a cold winter.

Yes, yes and yes. In places such as Port Hedland the water can be hot enough to scald. High free chlorine levels are maintained. Now that we have had some rain and the water table is restored the temperature has gone down again, but in Hedland it happens every year as the water table is all but non existant while the summer average air daytime temperatures are in the high 40s say 48. The ground heats up, the walls heat up, the only coolish water is where the airconditioning accidentally cools piping.

I have used both H/C- and only cold- fill washing machines. Where the ambient temperature is low, and the hot tank is the floor above the washing machine the length of pipe - even insulated - makes the hot-fill system less efficient.

The cold-fill will only heat enough water for the job, and at point of use, so our energy bills reduced when the cold-fill machine was purchased.

Here in the UK until last year hot and cold fill was the norm for our washing machines.

Since the thought police and fascist morons have taken over we now have only one machine perhaps no machine by now that has both hot and cold fill.

When I last purchased my Hot point washing machine it was the only make to offer this facility. when asked about this I was told it was all about energy efficiency cold fill was now a European requirement. The only problem being many powders don't dissolve at bellow 30C. The problem is ill informed idiots that always no nothing but have the power to mess with our lives for the sake of protecting their jobs.

I hate to think where it is all heading I am glad I am not a young person just having to grow up in this rotten world they have so messed up.

Brainwave,

I feel cheerful this morning because I have managed it through another winter back to British Summer Time - I find the light evenings so much more enjoyable.

Nothing to do with this thread, but your comments sound like a really unhappy and negative attitude.

There are many many things which are so much better now, than when I was young, and many of them have been designed and developed by bright engineers using their talents for good and taking pleasure from their achievements.

Hello yes when you have my circumstances you would indeed feel rather hard done by. I am in the W,Midlands arte do not have your advantage of being close to the coast. 75 90 miles from here. Because of poor health and having been made redundant 4 times tried to run my own business but too much red tape and lack of support scuppered that venture. I am now over fifty so I have had enmough of all the worlds wonders. I have been a sevice engineer, and worked both in avionics and private industry, so I know a thing or two about the comercial world design and all the problems that go with trying to make it in the world of electronics and engineering. This latest government has done absolutely nothing to help industry all I have done of late is watch good hard working folk get kicked out to rot on the dole.

Over 65 thousand so far this last 5 years. So I have no reason to be optimistic. Sorry if I sound bitter but I have very good reasons to be this way. I just hope you can have a better life than I have so far. "Things can only get better?"

I've always known that it was not just in Scotland that the job situation was as bad, but at least we have more than 2 parties and some variation in prospective policy.

It doesn't make any more jobs available here yet, though.

Plenty of jobs out here mate. Our previous Labour governemnt created so much unemployment we now have a huge skills shortage and workers are being imported hand over fist. Drop on down you'll probably like the warm weather too.