In thermal efficiency terms, a new larger cylinder is better. But the cost of a new cylinder is a large proportion of the total cost of a solar installation.

Retaining the existing cylinder by fitting the Solaplug is often thermally almost as good & saves a lot of money, making the Solaplug installation financially much more efficient.

Will a solar hot water heating installation using the Solaplug save money?

If you have oil or gas heating, typical annual fuel cost savings with any solar installation are modest. In order to at least break even over the life time of the solar system, the installation cost needs to be low. The Solaplug was invented with this in mind, it makes solar hot water heating more financially efficient.

What are the other benefits of solar hot water heating?

1.   You could be reducing CO2 emissions by 400kg per year.

2.   Using the Solaplug, CO2 emissions saved per £ spent will compare very favourably with other systems & technologies.

3.   From May to September, you could need little or no additional heating, which is a nice feeling.

4.   Your boiler will last longer, because it has less intermittent light work.

How can you explain the significance of CO2 emissions saved?

To put it in perspective, 400kg of CO2 emissions would be produced if you drove a small car about 3500 miles.

What size is the immersion heater? Where could I buy a spare?

The immersion heater has a 1.25” threaded boss, which is a common size in Europe. The immersion is 2KW, and has a thermostat, high temperature cut out & is RoHS compliant, to satisfy all UK regulations. The element is incoloy 800 to withstand even the hardest water. Spares are available from Solaplug.

1.25” immersions are used in commercial & industrial applications. Backer & Howden are two UK manufacturers, who can make immersions to this specification.

Can the Solaplug be fitted to a pressurised cylinder?

In practical terms, if the immersion heater threaded boss is 2.25”, the Solaplug can be fitted & work perfectly. We are seeking approval for this.

What is the power of the heat exchanger?

Heat exchanger power is dependent on surface area, material thickness & conductivity, as well as temperature difference.

The heat exchanger will cope well with any collector up to 3 sq meters.

What is the size of heat exchanger area?

6000 sq cm.

Will the heat exchanger be affected by limescale?

All cylinders & pipe work can be affected by limescale, the severity of the problem depends on hardness of the water & the plumbing system. Although some people consider that corrugated stainless steel heat exchangers attract less limescale because of the shininess & flexibility of the hose, we are unable to confirm this yet.

Where should the lower temperature sensor be fitted on the cylinder?

It is important that all the temperature sensors are fitted ensuring good thermal contact & are attached securely. Sensors which become loose will give poor temperature readings & adversely affect the performance of the system.

The lower sensor should be at the same height as the midpoint of the Solaplug heat exchanger. If there is a pocket for a temperature sensor at about this height on your tank, use it. If not, cut a hole in the foam & cover the sensor in thermal contacting paste before pushing  the sensor into the foam with a good thermal connection with the wall of the cylinder. Use a strap or tie to hold it in place.

What size pipe work should I use in the solar circuit?

Plumbing connections on the Solaplug are ½” BSP parallel male threads with large flat surfaces suitable for the DN12 nut & washer connections. The Solaplug is intended for installations with collectors up to 3 sq meters.
It is recommended that the flow rate through the circuit should be 40litres per hour per sq. meter of collector. For a 3 sq meter collector the flow rate should be 120 litres per hour.
The speed of the flow of coolant should be less than 1 meter/sec to avoid vibration & noise.
The internal diameter of the pipes must be greater than 6.4mm.
Flexible stainless hose of DN10 & above or copper tube 10mm OD or above are all suitable.
If copper tubes are used, the joints must be compressions joints or high temperature solder, to withstand the very high stagnation temperatures.

With a vertically mounted immersion heater the pipes to & from the collector pass through the top of the cylinder, which is often hot. How is heat transfer from the top of the tank to the return flow to the collector minimized?

We designed the Solaplug with this issue in mind, solar heat must be transferred in the right place in the cylinder.
The solid return flow pipe from the heat exchanger to the brass body is lined on the outside. The return flow passing through the brass body is lined with silicone tube, to minimize unwelcome warming of the return flow to the collector.

 Is the Solaplug WRAS approved?

(Water Regulations Advisory Scheme)