Q. I am currently heating my pond using a gas boiler and stainless steel heat exchanger.Unfortunately I have only a rough idea of the heating costs. I would like to know where I can purchase a counter to fit to the boiler to keep an accurate time the boiler is running and then work out the costs.

A. These counters are usually available at large heating suppliers or electrical outlets. They are also available from RS Components, These are 230 volt and so can be connected up in line with thepump so that it is running only when the boiler is operating.

Q. I intend to have a combination boiler fitted in my house, and use my existing boiler to heat my pond. As the pond boiler is housed in the garage and is already fitted with a header tank in the loft above albeit on the large size, is it possible to use this header tank instead of an expansion vessel?

A. If the boiler is already installed in the garage then this is ideal. The header tank is the cheapest solution, but in the systems installed by our members the boiler housing is far away from the house and the expansion vessel is the only solution.
The header tank must hold at least one gallon, and be fitted with a water supply and a ball cock. On completion of the installation the system must be checked out by a qualified "Corgi" fitter before it can be used.

Q. In the paragraph along side the costs of heating a pond it says that the costs could be greatly reduced by better control of the temperatures especially in the Autumn. Would it save money to have a more accurate thermostat?

A. This statement that the costs could be greatly reduced by better control of the temperatures actually refers to the manual control of the thermostat. If you wished to minimise the running costs then as soon as the temperatures fall in the Autumn then you could reduce the thermostat, or even allow the temperatures to fall without the heater being switched on.
As their is a chance the temperatures will rise again then I do not reduce the temperature in relation to the weather, but prefer to keep the pond temperature in the sixties as long as possible.

Q. Is 170,000 btu heat exchanger the correct size for a 4,000 to 6,000 gallon pond?

A. It is difficult to get an exact answer to this, but having talked to several experienced dealers it appears to be the correct one.
The main criteria to consider is the size of pond pump you are going to use with the system. The maximum pumping rate through the heat exchanger according to the manufacturer's figures are as follows: -
60,000 Btu = 900gals/hr., 100,000 Btu = 1440gals/hr., 130,000 Btu = 1860gals/hr., 170,000 Btu = 2460gals/hr., 230,000 Btu = 3300gals/hr.

Q. Having just completed my 3500 gal koi pond I was wondering if their is a common temperature to which people heat their koi ponds?

A. In theory, overwinter temperatures of 55-60oF should be OK. 55oF is just high enough to keep the immune system operating without breaking the bank.
Summer temperatures around 70-80oF is ideal and will give you lots of. growth.
In Autumn and Winter, use heat to smooth out the temperature curve.

Q. I am thinking of heating my pond and am in two minds whether to go for a gas or electric heater as I have been told the new electric stainless steel heaters are economical especially with gas prices on the up. My pond is only 2000 ltrs and will be insulated. I would appreciate any comments.

A. So called "Modern" Stainless steel heaters still use a basic resistive wire heating element so I doubt if they are any more efficient that older versions to be honest. Electric heating is cheaper to install that gas heating but more expensive to run. That said, on a well insulated 2000 gallon Koi pond, a 2KW heater, used sensibly should be fine.