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April 26, 2024

Solar water heating system, not getting the water hot on overcast rainy days? - How to Repair

Solar water heating system, not getting the water hot on overcast rainy days?

by / Tuesday, 20 December 2022 / Published in Solar Solutions

For your local supplier or Quotes on Swimming Pools, Please contact HotSolarWater Direct

The three main things you should always do with solar water systems for maintenance

  1.  always inspect the Anode every couple of years, this is what stops corrosion from taking place inside the tank. It prevents electrolysis.
  2. I personally would always replace the heating element every 5 to 7 years preventive maintenance is the best way you don't want to have to be going on your roof when it's tipping down with rain because the heating system has failed.
  3. Every 5 to 7 years, I would always replace the glycol in the panel and heat exchange unit. This stops corrosion, as well as stopping any liquids, freezing on cold winter nights.

Solar water heating systems are also known as geysers and thermosiphon systems. they are a great way of heating your water for free. They are really suited to Mediterranean type climates where you have a lot of sunshine, but they heat the water very efficiently even on cloudy days, but sometimes it does not create enough hot water for the whole household. This is why electrical systems are fitted to the tanks as well.

 

Hotsolarwater.com was good enough to send me some exploded diagrams so you can see how the tanks are constructed and how to also go about measuring up to replace either the anode thermostat or the heating system.

 

 

Here is a pool and hot tub we installed at the same site 5 years ago

150 L and 300 L Thermosiphon Geyser Solar Water Heaters

Please contact hotsolarwater.com for all quotations

For Quotes on Swimming Pools or overseas systems Please contact HotSolarWater Direct

Our aim with our meters and solar water heaters is to improve water efficiency and cost to every household.

Before Buying solar electric you need to address the items that cost the most to use and Water heating is the highest cost in most houses.

These figures below are for 1 person not including the water you use for washing up ETC.
The lifespan of normal electric or gas boiler knower days can be between 5 to days years max, costs can start from £300 to £1000 plus fitting.

Solar water heaters start from a £1000 but are totally free to run.                           Click Here for Pricing
Lifespan in excess of 20 years if fitted and maintained properly.

Daily & Annual costs of Heating Water:

Heating water to have a bath or shower can be a major cost on your energy bills depending on how you heat the water and how much water you use. This changes from country to country but we will look at the UK for now. water temperatures There are many other factors including the temperature of the cold water entering the heater system, the temperature of the hot water coming out of the heater and hot taps and the cost per kWh of the energy. Bath sizes in the UK are limited to a maximum of 230 litres but the average water volume used is about 80 litres. Some manufacturers try and design the bath form to reduce the amount of water required to have a full bath. Showering instead of taking a bath can also be an option to save water but the energy cost to heat the water depends on the type of shower, water pressure, flow rate and method of heating the water.

Water mains temperatures in the UK (Average  7.3C) are much lower than Spain and Portugal (Average 15-20C) but the cost of energy is much higher but these principles will be the same.

There are many other factors including the temperature of the cold water entering the heater system, the temperature of the hot water coming out of the heater and hot taps and the cost per kWh of the energy. Bath sizes in the UK are limited to a maximum of 230 litres but the average water volume used is about 80 litres. Some manufacturers try and design the bath form to reduce the amount of water required to have a full bath. Showering instead of taking a bath can also be an option to save water but the energy cost to heat the water depends on the type of shower, water pressure, flow rate and method of heating the water.

In our comparison below we have shown the costs of heating water to have a shower or fill a bath of different volumes to 40°C using three different methods; an electric immersion heater, a modern A-rated gas boiler and solar water system.

Daily costs: heating water for shower or one bath this is only for 1 person and multiply the figures for your household. 

 

 

 

 

Annual costs: For shower or heating bath water for one bath for 365 days a year.

 

 

 

 

Last calculations made 2015.

T1 = Temperature of cold water entering system in Kelvin (K)
T2 = Temperature of hot bath water in Kelvin (K)
V = Volume of bath water  (litres)
S = Specific heat capacity of water is  4.18 J/cm3/K
Be = Boiler efficiency (A-Rated is assumed 90%)
EJ = Energy required heating water in Joules
EB= Energy required heating water with boiler efficiency adjustment
C = Cost to heat one bath or have one shower.

  • The assumed water temperature entering the heater is 10°C.
  • The assumed water temperature leaving the heater into the bath is 40°C.
  • Energy prices are taken from the Energy Saving Trust website based on the average rate for domestic households in England, Scotland & Wales, last checked February 2015.
  • Electricity average price (Standard Rate) : 14.05 pence / kWh
  • Gas average price (Standard Rate): 4.29 pence / kWh
(EJ) The energy required to heat the water in Joules is therefore :
EJ (in Joules) = S x (T2-T1) x V x 1000

Adjustment  to account for the boiler efficiency (EB in Joules) is therefore :
EB (in Joules) = EJ x  ((1 + (100-Be)) / 100)

To convert Joules to kWh (1 kWh = 3600000 Joules) is therefore :
EB (in kWh) = EB (in Joules) / 3600000

(C) The cost to heat one bath or shower in kWh is therefore:
C = EB x Energy price per kWh

 

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