solar water heating issue

C

CloudAx

New Member
Messages
1
When solar water heating was installed the boiler connection was moved to the upper coil in the tank and the solar connected to the lower coil, as standard procedure. However, now in winter our boiler doesn't heat enough water for even 2 showers (we used to get a lot more). So we're considering swapping round which coil boiler/solar connect to and having the boiler on the lower one as it used to be. Does anyone know if there's a good reason not to do this?
 
I presume this is a thermal rather than PV solar system? I'd suggest first step would be do investigate why the effectiveness of the solar has decreased. It could be that the thermal liquid circulant in the system has evoparated and needs topping up (something that was never really mentioned when these systems were all the rage prior to PV). Also on the physics principle of hot water rising, your uppermost coil should be allocated to the most effective heating method (which would currently seem to be the boiler) so I wouldn't tamper with this arrangement until I get to the bottom of the other. Aim for a review of your solar configuration/maintenance schedule first
 
Mayo1969 said:
why the effectiveness of the solar has decreased
Click to expand...
CloudAx said:
winter
Click to expand...
Am I wrong in thinking that you are trying to do something very complicated when there is a much simpler answer?
In the time it takes to have 2 showers, the boiler should be able to recharge that heat. Just heat the water when you get into the shower.

Alternatively, if you have a good night time rate (7-12c, 100% efficient), you can use the emersion heater to heat your water for roughly the same cost as the gas (10c <75% efficient). But you will need decent insulation on tank to keep the heat in the tank. I found an old duvet and a few old pillows worked really, really well for this.
 
The solar coil should always be at the bottom of the cylinder.
This is because in winter the solar panels will only be able to raise the water to a lukewarm level. This prewarmed water then rises up to the level of the boiler coil to be boosted up to working temperature.

Is the thermostat on your boiler set to a sufficiently high temperature. If the boiler is not heating the water in your cylinder up enough you will be using hot water only to your shower. No mixing with cold. This means that a larger volume of hot water is taken from the cylinder for each shower.

Your boiler should be heating the water in the cylinder to a minimum of 55 degrees C. This is necessary to prevent legionella in the hot water supply.
 
S class said:
The solar coil should always be at the bottom of the cylinder.
This is because in winter the solar panels will only be able to raise the water to a lukewarm level. This prewarmed water then rises up to the level of the boiler coil to be boosted up to working temperature.

Is the thermostat on your boiler set to a sufficiently high temperature. If the boiler is not heating the water in your cylinder up enough you will be using hot water only to your shower. No mixing with cold. This means that a larger volume of hot water is taken from the cylinder for each shower.

Your boiler should be heating the water in the cylinder to a minimum of 55 degrees C. This is necessary to prevent legionella in the hot water supply.
Click to expand...
Presume the Solar Thermal to Bottom coil is to allow the full cylinder of tank of water to be heat as of an when the incidence of solar allows. Otherwise in summer, only the top tank of water is available for domestic use, the potential of the system being unneccessarily limited,
 
Xelfyou said:
The thermostat switches off automatically when the temperature reaches 60' / 70' Turns on again when say you run the shower..
Click to expand...
As above, even with a factory insulated tank that's an unnecessary waste of electricity, and increasing the volume of on/off cycles will shorten component life.
 
Leo said:
As above, even with a factory insulated tank that's an unnecessary waste of electricity, and increasing the volume of on/off cycles will shorten component life.
Click to expand...
Install an immersion timer so...
 
Yes, that was the point! It would likely be cheaper to hit boost on the boiler when the first person is going for a shower, though experience will vary on the efficiency of heat transfer to the tank and pipework insulation.
 
You must log in or register to reply here.
Back
Top