N.Design Studio

Pond heating

Updating a system on a 6,000 gallon pond - page 1.

When Mark & Ritta built their pond in 1989 they used a Laars Telydyne 125,000 btu swimming pool heater to heat the pond, and this has worked well.
For many years this was the most popular heater used in this country, but these have now lost popularity as these earlier models did not have stainless steel heat exchangers. There has been some concern amongst koi keepers that the copper and other non ferrous materials used in the heat exchangers could leak into the pond water and cause serious problems with the fish.
It was therefore decided to change the system and install a central heating type boiler with a separate stainless steel heat exchanger. We will now follow the installation and discuss the reasons for some of the decisions taken.

BOILER.

This photo shows the original boiler. The new boiler was to be placed in the same position, but with modern design and technology they are now quite small so this would not be a problem, and there would be room for the heat exchanger and the pressure tank.
It was decided that a floor mounted boiler with a conventional flue would be used in this case. A wall mounted boiler with a balanced flue could have been used, and would be the best choice in most cases. The other side of this wall faces on to the front garden and can be seen from the road so this was not an option. The replacement boiler was a Potterton Kingfisher.

TIP. A Baxi boiler had been on the short list, but the manufacturer stated that their boiler could not be used with a pressure system. This is something that must be checked out if you are purchasing a central heating boiler to be used in these systems.

HEAT EXCHANGER.

The stainless steel heater exchanger is the type used for heating swimming pools, and they are available in several sizes. The governing fact regarding the size required is the maximum pumping rate of the pumped pond water as stated by the manufacturers.
This pond is 6,000 gallons and the swimming pool pump used delivers 3,000 gph. The heater exchanger used was the 230,000 btu model, and this is rated by the manufacturers at 3,300 gals/hour.

Mark & Ritta arranged to carry out the work over three days, and a hot period in July ensured that the temperatures in the pond did not drop very much whilst the work was being carried out.
To achieve this deadline all the main parts were purchased, and checked. Then a list of all the fittings required was made up and purchased, so that there would be no delays when the work was started.

HEAT EXCHANGER ASSEMBLY.

In the photo above the parts for the pipework have been laid out so that they could be measured and assembled. As everything was to be placed within the area previously used then it was essential that everything was carefully planned so that not only would they fit into the space, but that they would look as neat as possible.
In this photo the central heating pump complete with shut off valves has been connected to the inlet side of the heat exchanger. The 15mm pipe is for the air vent, and is laid on the thin piece of wood to allow for the thickness of the munsen clips which will attach it to the wall.
A drain cock A has been fitted between the pump and the heat exchanger.

TIP. For items like the stainless steel bends and brass compression fittings needed to attach the 22mm copper pipe to the heat exchanger it is a good idea to take the heat exchanger to your supplier, and he can then supply you with the correct parts.

SYSTEM ASSEMBLY.

The next step was to assemble all the parts in the garage on the first day so that it could all be transferred outside on the second day.
The step in the wall on the right hand side of the photo was used as one boundary. The width of the space outside was then marked with chalk on the garage wall. The boiler was then put in place relevant to where it will be permanently fitted, and its position marked on the wall and floor again with chalk.
The pvc piping has been put in position so that the exansion vessel could be correctly located.
At this stage the heat exchanger was put into place, and supported in the correct position by wooden packing. This would now allow the other parts and pipework to be built up and assembled ready to move outside the next day.

PRESSURE/EXPANSION VESSEL.

The pressure vessel and the expansion vessel have been unpacked, and are laid out ready for assembly.
The bracket cannot be seen as it is supporting the pressure vessel.
The three copper fittings in the top right of the photo are not part of the fitting kit.
The flexible pipe is included, but the yellow and white plastic fittings have been added to suit the hose pipe which will be used for filling the system.

When the boiler system is installed indoors then there is a small plastic expansion tank in the attic which pressurises the system. This is not possible when the system is used outdoors so the pressure/expansion vessel has to be used.
This equipment is made by "Flamco", and has a capacity of 8 litres.
The vessel and parts have now been assembled and are ready for fitting.

SYSTEM ASSEMBLY.

This photo shows the assembly at the end of the day. All the copper pipes has been assembled in position, and are connected at the back of the boiler.
Air vents have been added to the pipework at both the suction and discharge sides of the pump. These should be added at the highest part of the system, but in this case was not possible on the suction pipework due to the preformed 28mm pipework supplied with the boiler.
This assembly is now ready to be put in position tomorrow when the original boiler is disconnected and removed.

WARNING. Care must be taken when building a system such as this unless you are conversant with this type of work. If you are not qualified to do the wiring yourself then consult an electrician. In Great Britain it is a criminal offence to connect the gas system yourself, and this must be done by a CORGI registered fitter. If you are doing this in any other country then do get expert advice and make sure that all the installation and work confirms to local regulations.