Flat/pitched roof questions
We are really keen to get a system however, as mentioned I do want to flat mount onto the roof rather than with a platform.
If the roof is flat (up to 15˚) the NS-200WB/22 SLIMLINE version will sit flattest on the roof with the tubes being at approximately 22˚.
If you have a pitched roof over 15˚ the Standard NS-200WB/45 will be the way to go. This version is designed to sit at 45˚ on a flat roof and can be cut down at the rear legs to sit flash (relatively) on a pitched roof up to around 40˚.
Evacuated tube systems can be installed on the west side with efficiency being also near optimum.
Also – I see in your youtube clip that there is a small header tank. Is this necessary?
The header/re-filler tank is designed to re-fill the main tank when there is excess boiling or steaming, this is normal with evacuated tube solar hot water systems, especially in spring and summer when they work at 93% efficiency.
You can remove the tank however you would need to top it up every couple of months to make sure it is full and working at maximum capacity.
Also of note, we are on tank water with a water pump so pressure can go up and down slightly with the pump coming on/off – is this ok for the system?
Yes. The system is ‘pressure in > pressure out’ so it can cope with mains or pump with no problems, in fact it works far better with a pump as opposed to Gravity fed systems.
As mentioned we designed the house with solar hot water in mind. Also the plumbing for the wood fire to be connected. I am a little concerned whether the system will be big enough – is there a ratio on how much water allowance I should give per person? I haven’t found a decent guide online.
Normally a wet-flue with a NS-200WB is ample for 2-4 adults. This does vary with factors like:
- Temperature of showers (normally 35-38˚ for 5 mins at 6L per/min = 30L)
- How many people/showers per day
- How many hours of sun & how many days of sun
- Whether timber is dry/green/hard wood/soft wood
In optimum conditions in summer, the NS-200WB will produce 200L of water at 95+˚C.
This would equate to around 350-380L of hot water at the tap at 50˚ (maximum temperature allowed in a domestic environment).
- 17–18 six-minute showers
- with a 6 L/min shower head
- assuming:
- hot water at 50 °C
- shower temperature 35 °C
- cold water around 15 °C.
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This would be in the ideal situation, in a normal or winter situation this could half.
This is a bit of a guesstimate without having accurate variables, but in our situation with 2 adults and 2 teenagers a 200L system was normally enough.
