Page 4 of 5 FirstFirst 1 2 3 4 5 LastLast
Results 61 to 80 of 84
  1. #61
    Join Date
    Jan 2012
    Location
    durban
    Age
    58
    Posts
    1,724
    Thanked: 1930

    Default Re: New building - what geyser options

    Quote Originally Posted by Fluffy View Post
    Dear Sir, please don't take this badly or personally.

    I am sorry but try as I may I just cant read or absorb that.

    Sorry, genuinely sorry, maybe I am just doff..,,,,
    We all know you are not doff so please elaborate ,what you didnt get. Some of what he says makes sense. Im curious as Im still on a learning curve with all this.

  2. #62
    Join Date
    Oct 2013
    Location
    Centurion
    Age
    65
    Posts
    2,982
    Thanked: 1297

    Default Re: New building - what geyser options

    Quote Originally Posted by plunger View Post
    Its not the size or make of h pump in this case ,but rather the size of the geyser. Its asking too much to cater for seven people. Obviously how they use there water will dictate how much hot water they need.
    Well we might not agree on this point but we have talked about the loading valve before. It makes a big difference and also if you can use the whole capacity of your geyser before the cold water and hot water is mixed like in some heat pumps. The reason for asking about the size is that if a small heat pump is used it will battle in winter.

    Fluffy would be able to explain in more detail around the loading valve which is employed in his and my heat pump.

    As a user of a heat pump for 8 years I think I can comment on it's use. A 4.7kw power using 1.2kW from the grid is about the minimum for a 150L geyser. I have seen some lower power units and unhappy owners. Ask me as my installer fitted a different make than what I wanted only to remove it 2 days later and install what I wanted.

    As far as comments on winter time heating the geyser. Yes in winter it used the same amount of grid power to an element geyser but it takes about 4 hours to heat the water. Thus one need not go for extra storage but rather allow more time to heat during the winter. The normal 1 hour before waking up needs to be extended to 3 hours. Rather stick to the heat pump working when it needs to and disable the timer in winter.

    If this time is too long then the normal heated element can be brought in to assist. Something which we have never needed in the 8 years.

    Lastly your comment around 7 people if more than 1 bath is taken in the evening is a valid point. Showering should not be a problem.
    Last edited by ekkekan; 2021/10/18 at 06:47 PM.

  3. #63
    Join Date
    Sep 2014
    Location
    Rietkuil, Suurbraak
    Age
    37
    Posts
    80
    Thanked: 48

    Default Re: New building - what geyser options

    Quote Originally Posted by BruceB View Post
    Agreed, but with an on demand geyser there is no tank for the bugs to live in.
    Just make sure the exhaust vents carbon monoxide to outside.
    Also, gas geysers are sensitive to pressure variation - install a min. 25liter pressure tank in-line with cold input.

  4. #64
    Join Date
    Mar 2008
    Location
    Cape Town
    Age
    49
    Posts
    288
    Thanked: 7

    Default Re: New building - what geyser options

    A few comments on solar and heat pumps
    In England they can get solar hot water for about 300 days a year. In South Africa we ge solar hot water for the summer only.
    Why is that?
    We do get a bit more than summer, but definitely no where close to 300 days

    It is because out solar is largely sized for summer so that is doesn't overheat
    Also most of our geysers are horizontal. Overseas most are verticle
    And because we don't have a decent solar geyser controller

    In the UK, they try to size for winter and use a heat dump for summer. You need a solar controller that has the facility for a heat dump
    Also mostly evacuated tubes and more of them.
    Works well on a decently designed system

    In very cold weather, our heat pumps don't work properly
    If I remember correctly, below 6 degrees, they can't absorb heat from the air and just above that, very little heat is absorbed
    Also ask any good refrigeration engineer that the most efficient fridge/heat pump, will be one that is designed to operate in a very narrow parameter. That is temperatures are constant.
    If the temperature is constant and known, then the gas and exact charge of gas can be calculated for the most efficiency
    Overseas, they often use a ground loop for the heat pump. As the earth's temperature remains mostly constant under ground and the temperature of your hot water is known, you can set the exact charge of gas for the most efficiency.

  5. #65
    Join Date
    Dec 2013
    Location
    Bellville
    Age
    57
    Posts
    10
    Thanked: 5

    Default Re: New building - what geyser options

    Quote Originally Posted by GreigD View Post
    The problem with electric geysers is that most people, me included, never have the sacrificial anode replaced as it should be, every two years as a minimum. This is fatal for an electric geyser and as soon as insurance companies wake up to this they will not want honour claims for “burst” geysers.

    The irony is that it is more expensive to change the sacrificial annode than to pay the excess amount on an insurance claim

  6. The Following 2 Users Say Thank You to Pieter J G For This Useful Post:


  7. #66
    Join Date
    Dec 2013
    Location
    Bellville
    Age
    57
    Posts
    10
    Thanked: 5

    Default Re: New building - what geyser options

    I have a heat pump for my main geyser and a gas heater for my kitchen sink. Both are the ideal for their application.

    The heat pump use about 0,8 kW energy to produce close to 4kW energy to the water. The coldest days is not a problem because Bellville does not get sub zero temperatures. On one of the coldest days I checked the controller - the air temperature was 5 deg and the refrigerant evaporating temperature was zero degrees so there was still a 5 degrees diffrence meaning heat will flow from the air to the refrigerant. Also my heat pump is in the roof space - less maintenance and more heat available.

    The gas heater in the kitchen is mainly for dishwashing. Gas energy is also expensive but wastage is less because you heat only the water you use. With a geyser you keep say 150 liters hot and there is constant heat losses which is energy that you paid for.

  8. #67
    Join Date
    Dec 2013
    Location
    Bellville
    Age
    57
    Posts
    10
    Thanked: 5

    Default Re: New building - what geyser options

    Quote Originally Posted by Dawid Rabie View Post
    Using at least 50 % energy from a sustainable source (not ESKOM) to heat water is not a city requirement it is a SANS 10400 Part XA requirement.
    Gas heating is not a sustainable resource.
    Although Heatpumps are up to 3x more efficient than the electric element in a typical geyser it is very slow and it is still using electricity?
    To make up for this disadvantage you need a much bigger volume water cylinder that will allow the heatpump to work for more hours during a day to build capacity because it cannot repond quickly to a sudden inflow of cold water.
    A 150l geyser would not be sufficient storage for a heat pump.
    Heatpumps also struggles to extract enough heat out of the surrounding air (..assuming it is an air to water heatpump..) to heat the geyser during the coldest weeks / months of the year when the incomming water is also colder.
    During those cold winter days supplemental electric or solar heating would be required.
    The same volume argument applies to solar water heating installations.
    Because the solar panels can not heat up cold water that flows into the tank at night the electric thermostat (if allowed to) will switch on the electric element and heat the water up to the geyers set point.
    If the electric elements thermostat is allowed turn on the element the moment it senses a drop in the tanks temperature at night it will defeat the main objective of saving electricity.
    To prevent this from happening you need to store a much bigger volume of hot water that will allow you sufficient hot water even after its been diluted and a GeyserWise type of controller to allow you work out if and when during a 24hr period or season the electric element is required to allow the occupants to have sufficient hotwater.
    Just maintaining the setpoint heat in a geyser 24hrs / day during the coldest times of the year require a substantial amount of additional energy.
    To avoid the long term maintenance hassel associated with a typical water / solar panel system I am of the opinion that a PV system that supplies electricity to the element in a geyser that have sufficient volume will achieve the same objective as long as it is also controlled by a programmable timer.
    I disagree with some points. Heat pumps are slow? heating time in hours is your mass of waterx4.187xtemperature diffrence/ heating kWx3600. This formula does not care if the kilowatts are from an electric element or a heat pump. Your water cylinder must be sized for peak demand

  9. #68
    Join Date
    Jun 2013
    Location
    Pretoria
    Age
    40
    Posts
    15
    Thanked: 3

    Default Re: New building - what geyser options

    Quote Originally Posted by ekkekan View Post
    What size heat pump did you use that battled in winter?
    Make
    I have sized the heat pump not to overload the inverter, thus 1,2kW was about the max. The problem I am experiencing is that its not heating quick enough when hot water is in high demand. For normal and low demand it's quite sufficient.

    But, even though the discussion is now mainly off-topic, If I can redo the entire system, I would just add a few extra solar panels, and install a ac/dc element on the geyser as David Rabie also suggest. Its almost an install and forget option, that is until the cylinder spring a leak. In my experience gas is the highest maintenance option as the empty cylinder need to be loaded, transported, exchanged and reinstalled ever so often. Heat pumps is also suppose to be serviced annually.

  10. #69
    Join Date
    May 2009
    Location
    Hillcrest
    Age
    65
    Posts
    20,086
    Thanked: 10223

    Default Re: New building - what geyser options

    Quote Originally Posted by Pieter J G View Post
    I disagree with some points. Heat pumps are slow? heating time in hours is your mass of waterx4.187xtemperature diffrence/ heating kWx3600. This formula does not care if the kilowatts are from an electric element or a heat pump. Your water cylinder must be sized for peak demand
    The thing with heat pumps is their installation. They tend to mix cold and hot water when you draw off hot water. ITS have a patented control valve to stop that.

    https://itssolar.co.za/water-heating...ion-technique/
    Last edited by Fluffy; 2021/10/19 at 12:30 PM.
    Cheers

    ZS5KAD - PROFFESIONAL DUMBASS
    3 Land Rover V8's
    NA - TwinTurbo - SuperCharged
    A V6 and an inline 4

    If you fly or drive to an anti-Fracking meeting, you have no business being there and you wont get my ear......

  11. #70
    Join Date
    Dec 2013
    Location
    Bellville
    Age
    57
    Posts
    10
    Thanked: 5

    Default Re: New building - what geyser options

    My proposal would be to install a 100liter solar heater which feeds your currenrt cylinder. Just re route your cold water supply to first go through the solar heater. Hot water extracted from your cylinder would be replaced with hot water and your storage capacity is increased.
    Last edited by Pieter J G; 2021/10/19 at 01:00 PM.

  12. #71
    Join Date
    Aug 2009
    Location
    george
    Age
    47
    Posts
    284
    Thanked: 182

    Default Re: New building - what geyser options

    In our previous house, spec house built new, we has gas geyser. I probably saved 1k per month on electricity bill. Did not like running out of gas at the most unforeseen time.

    In our current house, we went with 2 x 15L geysers. 1 x Heat Pump. It draws a constant 1.7kw when it is working. Heats up 300L in 3 hours. Also saves me 1k per month. I installed solar, small Solis 3.6kw system. The solis drives the heat pump, pool pump, rest of the house. Never had an issue with heat pump in winter. I would vote for heat pump.

  13. #72
    Join Date
    Dec 2011
    Location
    Cape Town
    Age
    67
    Posts
    74
    Thanked: 59

    Default Re: New building - what geyser options

    Quote Originally Posted by Pieter J G View Post
    I disagree with some points. Heat pumps are slow? heating time in hours is your mass of waterx4.187xtemperature diffrence/ heating kWx3600. This formula does not care if the kilowatts are from an electric element or a heat pump. Your water cylinder must be sized for peak demand
    Pieter the project in question is in Pretoria not in Bellville.

    In July this year SA Weather recorded a day during which the minimum temperature dropped to -1.6

    I would just like to state upfront that I dont have an issue with heatpumps in fact I have actively promoted and accomodated intricate interconnected heating and cooling systems with heatpumps in healthclubs since the mid 90's
    The statement that they are slow must was made in contexts to the conditions in Pta.

    It relates directly to the fact that on multiple projects on the highveld there were atleast a 3 week period when HP's with 18-20Kl storage tanks were not able to meet early morning hot water demand.
    We did NOT discover this problem after the fact we knew that this was going to be a problem and the engineers designed and sized the components to meet the challenge.

    It also did NOT stop us from continuing to use heatpumps it simply meant that we needed to find a short term heating solution and all I am saying is Plan for it.
    You are correct that to heat a kilo of water will always require the same amount of energy the problem is that a heatpump cannot collect the required heat at the same pace when it is very cold outside versus hot outside.
    It will continue consuming electricity at its normal rate, but the yield will be less.
    If the hotwater storage is sized to allow for 50-70l/person and they use all that water in the evening the HP must heat the cold water that flowed into the tank or else they will not have hotwater in the morning.

    Not running the heatpump during the coldest period of the day 4am-7am when it is not at its most efficient will be a small saving.
    In order to achieve that the HP must collect and store a larger volume of hotwater during the hottest part of the day when it is most efficient.
    If sized correctly the water in the tank could still be at a suitable temperature after the evening shower / bath /wash up after dilution if it is not only a little top up from the HP would be recuired.
    or
    Do you size the tank to suit the HP's optimal efficiency in warmer months using a smaller tank and use standby electrically heating elements to heat the water in the winter when / if there is a short fall.
    A heatpump is expensive, it consist of at least 25 components, all crucial to its function. If any one of them fail (which is not often) the whole system goes down. They also dont last forever.

    A normal electric geyser is much cheaper to install and it relies on fewer components but as we know they also dont last forever.
    Electric heating using Eskom power is not energy efficient because the cost of electricity is expected to increase constantly.

    If we replace Eskom with a PV system that heats the water during the day with suffcient storage capacity minimal night time heating would be required.
    Has anyone done this?

    There are a number of unkowns associated with this project that will affect the advice/opinions that we all are providing.

    This thread started with the plan to build a flat.

    We dont know how many bedrooms / people would it have to accommodate?
    The population, the proposed heating system and available capital will influence the hotwater storage cylinders size if there is going to be one.
    A final year engineering project on Domestic Heatpumps / UP (2012) found that it is not financially feasible to install a HP if the population is only 2 people. 4-5 or6 made it much more viable.

  14. #73
    Join Date
    Oct 2013
    Location
    Centurion
    Age
    65
    Posts
    2,982
    Thanked: 1297

    Default Re: New building - what geyser options

    Quote Originally Posted by Pieter J G View Post
    I disagree with some points. Heat pumps are slow? heating time in hours is your mass of waterx4.187xtemperature diffrence/ heating kWx3600. This formula does not care if the kilowatts are from an electric element or a heat pump. Your water cylinder must be sized for peak demand
    Without making it a debate. The heat pump would use like 1.5kW from the grid to produce 4 7kW of heat. So the same formula cannot be used.

    As far as this problem goes I would use a Geyserwise and set times when there is a high demand to introduce the normal element. That way one can still heat at 50% of the normal element heating cost. Normally heat pumps only have a contact that closes to bring in a relay to provide power to the element at a say colder than 5 degrees.
    Only if the make is known can one indicate a possible suggestion. Do read the link Fluffy posted about the ITS. I have experienced some other makes in KNP rondawels and know not all heat pumps perform the same.
    Last edited by ekkekan; 2021/10/19 at 03:06 PM.

  15. #74
    Join Date
    Jan 2012
    Location
    durban
    Age
    58
    Posts
    1,724
    Thanked: 1930

    Default Re: New building - what geyser options

    Quote Originally Posted by Fluffy View Post
    The thing with heat pumps is their installation. They tend to mix cold and hot water when you draw off hot water. ITS have a patented control valve to stop that.

    https://itssolar.co.za/water-heating...ion-technique/
    This is also the case with kwikot.Their heatpumps can also be set to 62c whereas before only 55 degrees.
    Last edited by plunger; 2021/10/19 at 02:58 PM.

  16. #75
    Join Date
    Jan 2012
    Location
    durban
    Age
    58
    Posts
    1,724
    Thanked: 1930

    Default Re: New building - what geyser options

    Kwikot have come up with a pv system that runs on 3 panels but uses a standerd element, not an ac dc ptc element like geyserwise uses.

  17. #76
    Join Date
    Dec 2013
    Location
    Bellville
    Age
    57
    Posts
    10
    Thanked: 5

    Default Re: New building - what geyser options

    Quote Originally Posted by ekkekan View Post
    Without making it a debate. The heat pump would use like 1.5kW from the grid to produce 4 7kW of heat. So the same forme cannot be used.

    As far as this problem goes I would use a Geyserwise and set times when there is a high demand to introduce the normal element. That way one can still heat at 50% of the normal element heating cost. Normally heat pumps only have a contact that closes to bring in a relay to provide power to the element at a say colder than 5 degrees.
    Only if the make is known can one indicate a possible suggestion. Do read the link Fluffy posted about the ITS. I have experienced some other makes in KNP rondawels and know not all heat pumps perform the same.
    You can use the same formula - just see :

    ((200 x 4.187 x (55-15)) / (4.7x3600) = 2 hours for the heat pump to heat 200 litres of water. But efficiency varies depending on air and water temperatures so that you do not get 4.7 kW all the time. Then it will take longer. Also you may get suppliers that lie about the capacity of their heat pump. And I totally accept that colder than 5 degrees is not ideal for a heat pump.

    I am sure the original poster has by now a fair idea what he is going to do.

  18. #77
    Join Date
    Oct 2013
    Location
    Centurion
    Age
    65
    Posts
    2,982
    Thanked: 1297

    Default Re: New building - what geyser options

    Quote Originally Posted by Pieter J G View Post
    You can use the same formula - just see :

    ((200 x 4.187 x (55-15)) / (4.7x3600) = 2 hours for the heat pump to heat 200 litres of water. But efficiency varies depending on air and water temperatures so that you do not get 4.7 kW all the time. Then it will take longer. Also you may get suppliers that lie about the capacity of their heat pump. And I totally accept that colder than 5 degrees is not ideal for a heat pump.

    I am sure the original poster has by now a fair idea what he is going to do.
    My humble apologies. I missed the 4.7 that must be used for the type.
    I have found that the factor used varies depending on the air temp. In summer it is between 33 and 50%. What I found on mine at times it will take a long time to start increasing the temp as measured at the bottom or centre where the probe is. Then when it starts heating it increases much faster.

  19. #78
    Join Date
    Dec 2011
    Location
    Cape Town
    Age
    67
    Posts
    74
    Thanked: 59

    Default Re: New building - what geyser options

    Quote Originally Posted by ekkekan View Post
    Without making it a debate. The heat pump would use like 1.5kW from the grid to produce 4 7kW of heat. So the same forme cannot be used.

    As far as this problem goes I would use a Geyserwise and set times when there is a high demand to introduce the normal element. That way one can still heat at 50% of the normal element heating cost. Normally heat pumps only have a contact that closes to bring in a relay to provide power to the element at a say colder than 5 degrees.
    Only if the make is known can one indicate a possible suggestion. Do read the link Fluffy posted about the ITS. I have experienced some other makes in KNP rondawels and know not all heat pumps perform the same.
    Ekkekan, sound promising...

    I have looked at ITS's website and noticed that they claimed a huge improvement over the HP competition but there were no support diagrams about the actual engineering method or science... I will search for Fluffys ITS post...

    The person that started the thread asked the forum for advice about a few possible water heating system for his proposed flat.

    It is quite possible that I am wrong when see this as an opportunity to exchange ideas and learn more about this subject.
    it is quite possible that many others will see it as a pissing contest.
    Maybe the people that have tried different solutions to the ones we have experience in dont want to share their experiences with us?
    Then again I am hopeful that there are people that have invested a lot of time and money into a process that I know very little about that are prepared to tell us about it.
    Their experience is invaluable to us because it is real data not a theory. Sharing it with us is a bonus.
    We live in a fast changing world, we need open discussions & debate in order to remain current.
    There is also the off chance that someone might have an crazy idea that they considered but decided not pursue any further that someone else might pick up and develop to the benefit of everyone.
    Just saying...

  20. #79
    Join Date
    Jan 2012
    Location
    durban
    Age
    58
    Posts
    1,724
    Thanked: 1930

    Default Re: New building - what geyser options

    Quote Originally Posted by Dawid Rabie View Post
    Ekkekan, sound promising...

    I have looked at ITS's website and noticed that they claimed a huge improvement over the HP competition but there were no support diagrams about the actual engineering method or science... I will search for Fluffys ITS post...

    The person that started the thread asked the forum for advice about a few possible water heating system for his proposed flat.

    It is quite possible that I am wrong when see this as an opportunity to exchange ideas and learn more about this subject.
    it is quite possible that many others will see it as a pissing contest.
    Kwikot also use an unloader valve just like ITS

  21. #80
    Join Date
    Oct 2013
    Location
    Centurion
    Age
    65
    Posts
    2,982
    Thanked: 1297

    Default Re: New building - what geyser options

    Quote Originally Posted by plunger View Post
    Kwikot also use an unloader valve just like ITS
    A lot could have changed in 8 years since I got mine. Had a Kwikot installed against my wish and it was removed 2 days later. Those in KNP are Kwikots but I did not study the connections but I know you get very little hot water out then the temp drops real quick.

    Kwik pump does not show their unloader valve. Is it an option?
    Attached Images Attached Images  

Page 4 of 5 FirstFirst 1 2 3 4 5 LastLast

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •