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Plumber doesn't rate solar! Advice please.

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  • 01-05-2008 4:12pm
    #1
    SillyMonkey
    Registered Users Posts: 54 ✭✭


    Loooked into solar to a certain point. Decided it would be a good thing and am seriously thinking of getting it.

    Am getting ground source geothermal with UFH to heat the house. Originally the hot water tank (supplied by the geo crowd) was to be primarily heated with the heat pump. Then I decided to go for solar panels to heat the water and have the heat pump as back up.

    In fairness the plumber is not pushing me he just reckons the solar is not really worth it. According to him the cost of the hot water (running on night time rate) is feck all.

    I said that I just wanted to not use the heat pump to heat the water as much as possible (I know it only does so much). He said says that the solar uses a pump anyway and there wouldn't be much difference.

    Anyway he's really putting me off this (without pushing me lol) the way he's talking.

    Am I talking crap. Does anyone have any views on this or even better any actual experience I.E. using heat pump and solar. If you just went heat pump and not solar, why?

    Thanks in advance.


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    #2
    abakan
    Registered Users Posts: 546 ✭✭✭abakan


    that not really future proofing you house.

    Can you not add the excess heat generated with the geo thermal to heat the water in the house?


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    #3
    AckwelFoley
    Registered Users Posts: 12,556 ✭✭✭✭AckwelFoley


    The use of the solar with a heat pump is slightly differnet to that of if you were just using solar and no heat pump.

    Personally depending on where you get your solar based on cost, it can be worth it, bt the payback time on the investment is longer because the savings on your bill is smaller because you are saving on the amount of electrical use, that if fitted properly (the heat pump) will be relitively low. Its imperative that your house is very well insulated and done properly, and its important that your supplier, knows what insulation is being used and where so that they can spec the pump to match.

    The solar will contribute to the heating and will save you between 10 and 15% per year on your esb heating bill, presuming the panels are sized to suit the system.

    We generally sell the pumps without the solar panels becase of the fact that there is a longer payback on the cost of the panels, and because an air to water heat pump and combi tank cupplied and fitted can cost between 12 - 15k people feel they have enough spent at that point.


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    #4
    sinnerboy
    Closed Accounts Posts: 5,433 ✭✭✭sinnerboy


    snyper wrote: »
    We generally sell the pumps without the solar panels becase of the fact that there is a longer payback on the cost of the panels, and because an air to water heat pump and combi tank cupplied and fitted can cost between 12 - 15k people feel they have enough spent at that point.

    This does you credit snyper

    I trawled construct Ireland magazine for advarts for renewables suppilers together with contacts from the SEI website

    About 15 enquries in all looking for heat pump , solar , UFH and HRV .

    Most simply qouted as per enquiry but an honourabale 2 or 3 only advised broadly what you have posted here .

    My own view - if using a boiler ( gas / oil / wood pellet ) then solar is great to "rest" the boiler in summer and to "assist" it at other times .

    But high capital cost of HP together with the fact that HP + Solar both work most effeciently in summer means that costwise , it does not make sense to combine them .

    Might be worth spec-ing a cylinder capable of accepting solar at a later date .

    If solar panels come down in price and/or if fuel prices really accellerate , this may change the cost / benefit analysis


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    #5
    AckwelFoley
    Registered Users Posts: 12,556 ✭✭✭✭AckwelFoley


    sinnerboy wrote: »
    My own view - if using a boiler ( gas / oil / wood pellet ) then solar is great to "rest" the boiler in summer and to "assist" it at other times .

    But high capital cost of HP together with the fact that HP + Solar both work most effeciently in summer means that costwise , it does not make sense to combine them .

    Might be worth spec-ing a cylinder capable of accepting solar at a later date .

    If solar panels come down in price and/or if fuel prices really accellerate , this may change the cost / benefit analysis

    If you intend to use solar with the conventional systems like oil you need only a stainless steel tank, with 2 or 3 coils as required (im not a fan of triple coil tanks a combi is better but ALOT more expensive)

    You need the stainless steel tank from the get go. Even without ever using solar, its benefits on holding heat is great.

    If you have invested in this tank and decide to buy solar in future you will pick up a set of 36 evacuated tubes pretty resonable. The tank is nearly 50% of the total cost of a "complete" system. A 300l dual coil can retail from aprox 1200 to 1800 + VAT depending on where you source them


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    #6
    SillyMonkey
    Registered Users Posts: 54 ✭✭SillyMonkey


    Thanks for that lads.

    Actually asked the crowd i'm getting the heat pump from about getting solar aswell as the geo. They actually advised against it just for the simple fact that instead of 120-130 euro a year (E.S.B)for the hot water it would cost 60 ish with the solar aswell. So they siad there was little point. but of course if I really wanted they would sell it to me lol.

    :D


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    #7
    MickLimk
    Closed Accounts Posts: 188 ✭✭MickLimk


    SillyMonkey wrote: »
    Thanks for that lads.

    Actually asked the crowd i'm getting the heat pump from about getting solar aswell as the geo. They actually advised against it just for the simple fact that instead of 120-130 euro a year (E.S.B)for the hot water it would cost 60 ish with the solar aswell. So they siad there was little point. but of course if I really wanted they would sell it to me lol.

    :D

    I'm probably mistaken on my understanding of the figures above but on a back of an envelope calculation I figure that a 40-tube solar panel setup could provide about 1370kWh of energy (allowing for 10% losses through pipework etc.). This equates to about €206 of electricity at current prices.

    I know I've left out the factor of the solar pump (consumes a lot less power than a heat pump!) in this but I'm sure I'm missing out on something else here if a solar solution was only providing savings of €60-70/yr...

    EDIT:
    Penny finally dropped. The OP was talking about savings over what the comparative cost of running a heat pump versus solar savings and not heating by electric immersion. Sorry I misunderstood... :o


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    #8
    metalscrubber
    Closed Accounts Posts: 92 ✭✭metalscrubber


    "If you intend to use solar with the conventional systems like oil you need only a stainless steel tank, with 2 or 3 coils as required (im not a fan of triple coil tanks a combi is better but ALOT more expensive)"

    Snyper - two follow up questions for you if you don't mind ??

    Why don't you like triple coils?

    And what is a combi?

    Cheers,

    Metal


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    #9
    AckwelFoley
    Registered Users Posts: 12,556 ✭✭✭✭AckwelFoley


    Triple coil tanks are inefficent.

    Solar is always on the bottom, next the most used source, say.. oil and then on the top you will ahve your other source.. oil.

    Hot water rises, so in effect the coil on the top is only heating a very small portion of the tank, and you have to remember these tanks are very slim so at the end of the day you are not heating alot.. so a kind of a waste of energy.

    A combi tank is a tank within a tank.

    http://www.energymaster.ie/buffertank.asp

    The 2 down sides of this are first the price.. hitting around 3k and second.. it takes abit longer to heat the hot water internal tank

    We sell both, but the thing is that.. we always give the customer an option and let them know the differences and be aware of the ups and downs of both.. then they can choose...


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    #10
    RKQ
    Registered Users Posts: 2,292 ✭✭✭RKQ


    We have a geothermal heat pump, underfloor heating and solar panel tubes.
    Our geothermal has a boost facility to heat the cylinder but it never heated it?
    We had a 400 litre glass lined cylinder. We replaced it with a 300 litre cylinder after the coil burst in our original tank earlier this year. Only just over three years old! Expensive to replace!
    Our cylinder is 50 degrees at the moment, which is great for baths and power shower in summer.
    In winter the sun heats the cylinder by a few degrees which helps ease the time required to heat by emmersion.
    I was very happy with our tube system until the cylinder coil burst! Have problems trying to find out why it happened. Seemingly its unusual?
    Stainless steel cylinder is probably the better investment. Geothermal is fine for underfloor heating but no good for heating our hot water!


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    #11
    MickLimk
    Closed Accounts Posts: 188 ✭✭MickLimk


    RKQ wrote: »
    We have a geothermal heat pump, underfloor heating and solar panel tubes.
    Our geothermal has a boost facility to heat the cylinder but it never heated it?
    We had a 400 litre glass lined cylinder. We replaced it with a 300 litre cylinder after the coil burst in our original tank earlier this year. Only just over three years old! Expensive to replace!
    Our cylinder is 50 degrees at the moment, which is great for baths and power shower in summer.
    In winter the sun heats the cylinder by a few degrees which helps ease the time required to heat by emmersion.
    I was very happy with our tube system until the cylinder coil burst! Have problems trying to find out why it happened. Seemingly its unusual?
    Stainless steel cylinder is probably the better investment. Geothermal is fine for underfloor heating but no good for heating our hot water!

    To be honest, I'd certainly be concerned about a coil bursting in a cylinder. There are multiple safeguards supposed to be built into a properly installed solar system to relieve pressure so I'd actually hope it was a dodgy cylinder rather than an unsafe install!

    I don't suppose you happen to know what the system was pressurised to (on the solar loop) when this happened? Does your system have a proper high temperature expansion vessel? How about a pressure relief valve? Any chance you know the make/model of the original cylinder that had to be replaced?


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  • Options
    #12
    MickLimk
    Closed Accounts Posts: 188 ✭✭MickLimk


    MickLimk wrote: »
    I'm probably mistaken on my understanding of the figures above but on a back of an envelope calculation I figure that a 40-tube solar panel setup could provide about 1370kWh of energy (allowing for 10% losses through pipework etc.). This equates to about €206 of electricity at current prices.

    I used an incorrect figure at the start of the calculation above so the ultimate kWh figure is wrong. Apologies to anyone I may have misled about the figures above but I can't edit an old post. I found data on two different tubes and redid the calculations. The corrected (still back of an envelope!) calculations for anyone interested are in a new thread here: http://www.boards.ie/vbulletin/showthread.php?t=2055306224


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