# Solar, Wood Pellet & UFH?



## ciaranie (2 Dec 2008)

Hi, Just after getting solar panels fitted on garage(south facing roof). 10sqm flat panel. Using a wood pellet boiler Kunzel PL15 and a 750l buffer tank, 500l heating 250l DHW. Can the solar panels keep that amount of water warm during the day? Was wondering if I could turn boiler of during daylight hours and on when not? Can these systems be set like that? Everybody says ufh is most effecient when boiler is left on all the time but what do the solar panels do if the boiler is left on all the time?


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## sfag (3 Dec 2008)

The only solar panel you need during the day is the pane of glass in your window. if you have sunshine then your room will heat up from that and the thermostat will not call for heating.

The logic behind installation of solar panels is flawed. It only works when its sunny in which case you done need it. Doh.


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## sman (3 Dec 2008)

do solar panels make sense to get the water heated to a certain level even in winter so the boiler doesnt have to heat water from scratch. Also, in the summer you still need hot water for showers etc. if you do not have electric showers. For example with a pressurised system does it make sense to use solar panels?


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## skerford (4 Dec 2008)

I installed panels for the purpose of heating water for kitchen,baths,showers etc. and I never had to use the electric shower downstairs or turn on the heating  to get hot water from about start of May right up to middle of Sept, hot water even for showers available even at 11.00 at night and thats with the bad summer we had this year even.My parents are after finishing a new build 7 months ago and had them installed too and my mother is amazed with the amount of hot water generated. So i'm one of the rare people who say yes to panels on here.


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## Optimistic (4 Dec 2008)

skerford said:


> I installed panels for the purpose of heating water for kitchen,baths,showers etc. and I never had to use the electric shower downstairs or turn on the heating  to get hot water from about start of May right up to middle of Sept, hot water even for showers available even at 11.00 at night and thats with the bad summer we had this year even.My parents are after finishing a new build 7 months ago and had them installed too and my mother is amazed with the amount of hot water generated. So i'm one of the rare people who say yes to panels on here.



Lucky you. We had almost no hot water from our 8 sq mtrs of panels this year. IS it flat plate or tubes you have? How many sq mtrs? Our system is loosing pressure continuously. We are not heavy hot water users and only 3 people in the house. Optimistic


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## sfag (4 Dec 2008)

make note of the following.

1. Those who say they say they get their hot tap water from solar have not done their sums. It costs a quid a day to heat my very large cylinder via a gas boiler. Its peanuts. We never run out. 
Solar panels in this instance are a solution to a problem that does not exist.  skerford above does not crunch the numbers.

2. Any heating system that offers to complement or part heat your central heating water is just phoney sales pitch. A complete waste. Avoid.


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## ciaranie (4 Dec 2008)

sfag said:


> make note of the following.
> 
> 1. Those who say they say they get their hot tap water from solar have not done their sums. It costs a quid a day to heat my very large cylinder via a gas boiler. Its peanuts. We never run out.
> Solar panels in this instance are a solution to a problem that does not exist. skerford above does not crunch the numbers.
> ...


Have you any experience with these systems sfag?


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## bertie1 (5 Dec 2008)

I too have solar panels evacuated tubes,( 11 sq meters of roof space ) taken up 100 tubes in total heating a 450 ltr tank. Any day the sun was shining during the summer the tank heated up to between 50 - 60 C which meant that even with the bad summer the oil may have been turned on once or twice a week for a half an hour to top up the tank. Last summer it wasn't turned on at all from May to the end of September. 
If there was no oil being used for that time I recon I am on to a winner. Even today the in the middle of December the sun is shining , I expect the bottom of the cylinder at the solar loop to be around 40C ( with no heating on ) when I get home tonight

As for crunching numbers , yes the installation costs are high enough ( about 4000.00 to buy the panels + the plumbing) to put in the panels & the pipework, but ours was a new build & we put in the large cylinder to suit the house it just meant going for a dual coil. However I feel better that I am not paying to heat a whole tank of water when the sun is shining it is costing me nothing to run it & the sun is shining in any case ( the days it comes out) 

You may not see a return on it in the short term but with the new building regulations it is now compulsary to put in some form of renewable energy , and it will help your resale value when you go to sell later on.


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## skerford (5 Dec 2008)

Optimistic: flat plate directly south facing.

Sfag: I won't agree with you there as "complete waste". Fair enough if it cost you 1 quid a day for gas boiler but many people in this fair state don't have access to gas mains and for an average family with 4-5 people in a household (who we'll presume will take a shower maybe once if not twice a  day) with only electric showers your esb bill won't be long in running up.
Therefore I quite agree with bertie1 as it may not add up now to have it but 10 -15 yrs down the line it will especially with the new energy ratings affecting the price of your house, solar can only be of a benefit .


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## BD plumbing (5 Dec 2008)

i dont install the solar panels but i do everything afterwards the solar panels are desinged for giving hot water mainly you can use them for your heating but it wont be very effective to use them for your heating you need to have a heat exchanger installed between the solar panels and your buffer tank now the idea of a buffer tank is that it heats up in a certain amount of stages ie stratification also another name for a buffer tank (stratification tank) the solar panels would enter the bottom of the buffer tank and heat only a third of the water then you have usually a wood pellet boiler enter the tank around the middle of the tank and that would heat the centre of the tank and then youd have the gas coming in at the top of the tank now because hot water rises the gas boilers should not have to come on and are usually there only as a back up if the woodpellet boiler was to burn out from fault or lack of pellets this is when the gas would kick in during the summer it is possible for the solar temp to reach 200 degrees but this is reduced through the heat exchanger so this and the woodpellet should be more then sufficent to heat the buffer tank BUT during the winter months the temp of the solar can be as little as 20 degrees so the woodpellet would run for a lot longer during these months

so basically the water from the solar and the woodpellet and the gas all mix together in the buffer tank and inside the tank you have a coil of pipe going the whole length of the tank and in this coil you have your hot water going to sink and showers/baths this coil travels through the mix of hot water from the solar,woodpellet and gas and heats up your hot water

basically what im saying is that the solar wouldnt be enough to heat all the water in the buffer tank to sufficently heat your hot water and your underfloor/radiators as it will reach such a low temp in winter time solar panels work not from direct sunlight but by uv rays and due to the short time that we see the sun during the day its not possible to heat to the degree that it reaches during the summer i hope this helps you if you have any queries you can im me and ill give you a contact number and ill can have a chat and explain everything to you properly


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## ciaranie (5 Dec 2008)

What I'm Hoping for with this system is that the solar panels will heat most of the dhw and on good days will support the heating. During the summer on bright days it should do everthing but in winter when the boiler starts are the solar panels doing anything?


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## BD plumbing (5 Dec 2008)

yes they are providing a small bit of heat which means the wood pellet wont be on for as long as it would be without the solar hence saving you money in the long run


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## Mrs Aol (6 Dec 2008)

We have 12sqm of solar panels and a wood pellet stove with integral boiler. Over the last 12 months we've used less than 1ton of pellets for all heating and hotwater including showers and dishwasher. The house is 2500sqft and there are 4 of us. I'm at home during the day with the children so it needs to be warm/comfortable all the time. Our stove/boiler didn't really kick in from March until Oct and quite often these days it's not needed either. How can anyone say that solar panels are a waste of time etc?!


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## sfag (8 Dec 2008)

ciaranie said:


> Have you any experience with these systems sfag?


 
I have carefully monitored the cost of heating my cylinder water and it is so cheap there is no point in providing a solution. Thats the bottom line.

Life experience has thought me that any system which still needs another system as backup is a waste. You will never be able to quantify its contribution. In theory you can but not in practice. In theory air ionisers worked - in practice they were snake oil.

You have got to think about it. 
These solar things cost serious money. 
You only need sun in the winter. We dont get much sun in the winter. 
Most days its cloudy. Some days it will be sunny for a few hours. Today there is no sun. 

I have large facing windows on the south side of my house. 
For a few hours of winter sun they heat up the house in the day. That heat will last for a hour after the sun disappears.  
Thats good for weekends when i'm there during the day and I suppose it means my 24/7 ufh doesent have to work during the day when I'm not there. 

But there is no science to windows - they have been around for centuries. Their solar gain is a secondry benefit as - as far as I'm concerned - their reason for being is architectural.

If you want solar benefit get the greens to insist on all new builds having south facing windows.


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## ciaranie (9 Dec 2008)

So no experience. Is there anybody using this system that can help with the set up of it?


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## bertie1 (10 Dec 2008)

I have solar with oil underfloor heating , what exactly is it you need to set up . 

Our underfloor heating system has stats in each room & they are contolling the room temperatures

I currently run the underfloor 6 hours a day
16.00-17.00
17.30-18.30
19.00-20.00 
20.30 -21.30 
01.00 - 02.00 
05.00 - 06.00 
The house stays comfortable all day long with those times in our house
3000 sq ft bungalow, just topped up the oil tank with 750 liters of oil used since last May. The domestic water is on a stat & solenoid valve as are all the zones in the house & only come on when the stats call for heat. Stats are set at 18C 

When the weather gets milder I can turn back the running time of the boiler


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## ciaranie (10 Dec 2008)

Is your boiler not doing all the work there? Can the solar panels keep the water at the right temp after the boiler switches of?


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## bertie1 (10 Dec 2008)

The boiler is heating the underfloor. If the sun is shining the water temperature in the cylinder comes up over the setting of the thermostat on the cylinder and the solenoid for the cylinder doesn't look for heat from the boiler. On a sunny day this time of the year I get a tank of water ( if the sun is shining approx 40C at the bottom of the tank ) In the summer there are longer day light hours and the bottom of the tank can come up to 60c which lasts a few days depending on demand


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