The process and mechanics for heating swimming pool water comes in various forms but simplistically the object is to circulate water around the pool via a circulation pump in series with a filter and include ‘another device’ in the loop that transfers the heat into the water by absorption or induction.
This ‘other device’ uses an external fuel source of some kind to dissipate heat into the water. The device is better described as a Heat Exchanger; a piece of equipment built for efficient heat transfer from one medium to another. As described earlier, in series with the pool pump, effective heat is circulated through the pipework system; the efficiency of the system varies depending upon the power source behind the heat exchanger.
Obviously all this hardware and fuel usage comes in at a cost, these costs are very important to consider especially in current times where worldwide fossil fuel and other fuel prices are so volatile. Therefore the annual running cost has become the prime consideration; probably more crucial than the initial cost and service of the actual equipment.
Common fuel sources:
This article is aimed mostly at promoting the ‘air source heat pump;’ in the paragraphs below reference will be made to other heat sources mostly by comparison of running cost and efficiency.
The ‘air source heat pump’ is basically a waterproof, metal clad enclosure which stands out in the open air usually at ground level* and houses the heat exchanger module, cooling fan and integrated electronic control system. Without the enclosure the various components of the heater would be very recognisable as being similar to the equipment you would find on the rear of a refrigerator or freezer box. A coil of pressure pipework a pump or compressor and thermostat temperature controls.
*In some cases where there is limited space at ground level, heaters can be installed on a convenient flat roof or in extreme cases wall mounted.
Because these units pick up heat from the free-air around us, intensify it and transfer it into the pool water there are no large electrical components consuming huge amounts of power. The compressor, fan and controls use very little energy. The efficiency comes in the fact they the system can source heat even when the outside temperature is as low as -15°C* and still convert it into usable heat.
*Hydropro + series.
The following text taken from our website explains the principles of the technology involved quite well.
The unit contains a fan that draws in outside air and directs it over the surface of the EVAPORATOR (energy collector). The liquid refrigerant within the EVAPORATOR coil absorbs the heat from the outside air and the refrigerant becomes a gas. The warm gas passes through the compressor where it is compressed to form a very hot gas, which then passes through the CONDENSOR (water heat exchanger). It is here that the heat exchange occurs as the hot gas gives up the heat to the cooler swimming pool water circulating through the coil. The pool water becomes warmer and the hot gas is cooling down as it flows through the CONDENSOR coil, returns to its liquid form and, after passing through the expansion valve, the whole process begins again.
A typical air source heat pump of say 13kW capacity will deliver 13kW of heating benefit into the water and only consume 2.36kW of electrical power to run the machine. Compared to electrical, immersion type heaters that consume 13.0kW of power to deliver 13.0kW of heating. Oil and gas powered heating systems run at similar costs to electric heating; there is some benefit however from using solar energy systems, but the initial installation costs tend to be quite considerable and in some cases not aesthetically pleasing.
To capitalise on efficiency the size of the heater should always be correctly matched to the pool volume, if too small the heater could be running for much longer periods than necessary and consuming excessive power. There is also a danger of the machine failing due to almost continuous running. When the unit runs through its heating – cooling cycle ice tends to can gather on the heating coil, if running constantly this cycle is broken and can affect the efficiency, therefore accurate sizing and selection is critical. Our sales advisors are on-hand to assist with this selection process.
A good example of correct selection is for example a 6m x 3m pool with a varying depth of 1.5m – 2m at the deep end which has a total volume of approximately 31m³. The ideal machine for this pool is the Hydropro 10kW as it is good for a 40m³ pool. However some retailers may consider the Hydropro 7kW heater at less cost as it states in the documentation that it can accommodate a 30m³ pool. This in our opinion would be too small; the heater will not run efficiently trying to deliver sufficient heat to a pool too large for its capability. The 7Kw consumes 1.3kW of power and will be running pretty much constantly whereas the 10kW will run intermittently and consume 1.82kW. Calculating the running cost at £0.15/kW/hr. (rates vary and depend upon your local energy supplier) the two machines will cost £0.20 and £0.27 per hour to run respectively.
The efficiency of an air source heat pump is better described as the ratio of useable heat compared to the work or input required. Otherwise known as the coefficient of performance or COP Curve. Simply put it’s the relationship between the current, ambient outside air temperature times the temperature you have set the machine to attain and the work the set needs to do to attain it over a time period. Air source heat pumps can achieve very good COP figures compared to electric or other heat sources.
The actual pool water temperatures that can be attained depend on factors such as location, season, aspect and foresight on installation. Open aspect above ground pools lose a lot of heat from the wind blowing across the surface for example and dissipation through the supporting walls. Taking these into consideration and taking particular care on installation will help maintain usable temperatures.
In-ground pools and covered pools under a permanent roof do not have the same problems with heat loss therefore it would be quite reasonable to expect to realise quite comfortable water temperatures even when the outside air is as low as -10°C or *lower. Using a pool all-year round is more than possible using the Hydropro + models.
* Hydropro + heaters can find effective heat as low as -15°C.
Here is a link to the Automated Environmental Systems LLP website:
Models ‘ECO’ ‘Duratech’ and Hydropro are shown.
ECO. For the smaller summer season only and temporary above ground pools, such as the Intex range. Correctly selected and matched against the water volume these are a very economical option with regard to initial cost, installation and running. These have simple controls, easy set and maintenance. Ensure though the circulation pump is adequate as these tend to be basic and low volume.
Duratech and Hydropro. Essentially the same machine externally and internally, there are some minor differences and ‘badging.’ These machines will capture heat from air temperatures as low as -10°C and raise water to approx. 35°C. The maximum water temperature may vary a little depending upon the parameters mentioned earlier such as aspect, geographical position and heat loss through covers and pipework. Much more sophistication with regard to thermostatic and timer controls is available on these machines using an integrated microprocessor system. Also has the facility of a remote control panel which can be placed close by the pool for easier adjustment or placed in a pump room to prevent tampering.
The final siting of the unit is extremely important, the instruction and guidance manual states the dimensions for free space to be maintained around the machine. Also importantly air source heat pumps should always be installed out in the open air, not enclosed in any way. Do not be tempted to site the heater in a greenhouse for instance or an enclosed building even with air louvres, it will not work correctly and inevitably fail in service in these environments.
We always recommend that when customers purchase a heat pump they also buy a: Heat Pump Bypass Pipework Kit. This is a combination of 3 valves, 2 T’s and a length of pipework which makes set-up so much easier by controlling the water flow through the heat pump. Also it gives the opportunity to completely isolate the heat pump by ‘valveing’ it out of the loop if it’s not required in the system. I.e. when cleaning. These are very low cost items but save hours of engineer’s time when commissioning the heater.
When correctly set up and incorporating a suitably sized pool circulation pump/filter combination and maintained according to the manufacturers guidance these heaters should provide many years of reliable and efficient heating. They are sold with full instructions and a 2 year manufacturer’s warranty for peace of mind. Automated Environmental Systems have technically skilled sales staff and trained engineers on hand as a back-up should customers have any problems or technical queries.
Q. Enquiry from a builder. I’m building a new 3 bedroom house which is an ‘infill’ and the drains will be lower than the local sewers by 1 metre. I’m told I need a pumping station, which size pump station do I need?
A. As you can imagine we offer a wide range of packaged pumping stations for all applications in many sizes, for above ground and below ground situations. For a domestic property with three bedrooms initially we would need to abide by the local authority building control regulations with regard to ‘storage’ within the pump station. They require a chamber volume capable of holding an equivalent to: 150 litres/person for a 24 hour period. This is just in case of local power-outages or the rare possibility of blockages. This combined with the measurement for the drain depth will determine the size of the chamber best suited to your application.
e.g. 4 person population x 150 litres/person/24 hours = 600 litres. With the drain depth @ 1 metre it will require a minimum chamber size of 1.0m Diameter x 2.0m Deep tank with Dual 2” pumps on guide-rails. This chamber provides 780 litres of storage under the incoming waste pipe invert which adequately complies. Please see details via web-link. https://www.drain-systems.co.uk/product/2877
Q. What do you mean by ‘dual pumps’ and ‘guide-rails’?
A. Yes of course, dual pumping station means we install two submersible sewage handling pumps into the pumping chamber, a duty pump and a standby, which in turn are controlled via an electronic dual pump control panel to allow the second ‘standby’ pump to kick-in if there is a problem with duty pump or a blockage. It does this automatically and sets off a high level alarm to let you know there is a problem. That is also a valid reason for having the storage as mentioned, as it gives you plenty of time to clear the problem. The panel also has an ‘auto-exchange’ feature which maintains equal wear on the pumps by the pumps running alternately on each cycle.
Guiderails are connected to the base pedestal or internal pipework system with a top bracket and slide facility at the neck of the chamber. The pumps are lowered into the chamber down the rails and sit and seal on the base pedestals and can be simply removed again by pulling on the pump lifting chain. This is by far the most popular option due to its simplicity of operation and has no requirement for confined spaces personnel to enter the chamber.
Q. What can you offer for the incoming drainage and outgoing pipework; we have a 20 metre run and a 2 metre lift to the drains?
A. For the incoming drainage we supply a rubber pipe sealing grommet for the tank wall, you simply cut a hole through the wall with a hole saw at a convenient point for the ‘fall’ and use standard 4” soil pipe to bring the waste into the chamber. For the outgoing pumping main; as we have suggested a 2” pumping station, we would offer 63mm x 50mm (2”) Black MDPE pipework which is polythene pressure pipe available in coil lengths of 25m, 50m and 100m with the appropriate PP compression couplers and bends if required. We have other sizes available with regard to the sealing grommets and also can supply 75mm and 90mm MDPE.
Q. Can I use the Mini Foul pumping station as they are much cheaper.
A. Not really, not for a whole house system due to this ‘storage’ factor. The Mini Foul units are great for:
small one bed annexes, garden offices and changing rooms etc, where they are not the main system for handling the toilet waste. The storage capability is very limited on these with 560 litre as a maximum volume.
The 1.0m x 2.0m pump station is not that expensive really if you consider the components that we supply in the package and that it easily meets the building reg’s. Included are: the underground tank, two pumps with lifting chains, internal pipework & valves, pedestals and guide-rails, dual control panel (240v or 415v) with integral high-level alarm and level control floatswitches, pedestrian grade galvanised steel manhole cover & frame and rubber pipe sealing grommets. We also provide installation instructions. It arrives with you ready for your installation, excavation and concrete back-fill.
Q. From a contractor: I’ve been asked to supply prices for an underground pumping station to an industrial packaging warehouse where there are 15 staff. There is a 3.0 metre lift and a 70 metre pipe run, invert level at 700mm.
A. The storage factor for industrial applications is less as it wouldn’t necessarily be a 24 hour operation; it is approximately 50% of the domestic requirement. Therefore we recommend using a 1.25m diameter x 2.0m deep pumping station which will afford approximately 1500 litres of storage. Please view via web-link: https://www.drain-systems.co.uk/product/2942
On this application we would specify 3” pumps as they have a larger solids handling capability – approx. 80mm. If there is 415v/3 phase power available on site we would use our DGO Series 3” (415v) pumps for this and according to our calculations will deliver a flow rate of approximately 400 litres per minute at the end of the pipeline.
Q. How do you get to that flow rate figure and what size pipe is required?
A. We make a calculation to include the ‘pipe friction losses’ in the MDPE pipework and fittings which give us the additional ‘head’ generated in the ‘system’ which we add to the 3.0m existing static head. This figure is then transferred onto the performance graph of the pump where we read off the estimated flow rate. We do this as a matter of course with all enquiries to ensure we always provide the most efficient pumping solution for economy of use and cost.
On this occasion we would use 90mm MDPE x 100 metre coil. We also supply the PP compression couplers or connections to adapt from our internal pipework terminating at 3” BSP on the outside of the tank to the 90mm delivery pipe with a PP compression coupler.
Please view via web-link: https://www.drain-systems.co.uk/product/5130
Q. Question from an existing customer. I purchased a dual pumping station from you two years ago and it works just great with no problems we just give it a once yearly service for peace of mind. I need another one now for an extension to the camp site; it has 150 metres of 2” pipe already in situ and approx. 12 metres head. It’s for a shower block and two toilets. 240v supply only. What do I need?
A. According to our records we sold you a 1.0m x 1.5m chamber last time. If that chamber is O.K. size-wise we could install into it one single 2” grinder/macerator pump which is a better proposition for you due to the high head and the long pipe run on site. As we discussed before grinder pumps are more expensive to purchase in the first place and tend to be expensive to repair; but in this circumstance it is really the best and only option for you.
We would fit the pump onto a 2” single pump guide-rail and pedestal assembly with adapters that we keep here, including the usual lifting chain control panel, 2 floatswitches and a pedestrian manhole cover etc.
A Pumping Station is a mechanical device installed in a sewer or water system or other liquid-carrying pipeline to move a liquid to a higher level.
Sewer pipes are generally gravity driven. Wastewater flows slowly downhill until it reaches a certain low point. Then pumping, or “lift,” stations are sited at this low point and push the wastewater back uphill to a high point where gravity can once again take over the process.
The pump station discharge pipe is a continuous main through which sewage or effluent is pumped and running full and at a pressure greater than atmospheric, to a final destination.
The pumping station itself is usually an underground structure that the foul (or surface water) sewage is discharged into. The types vary but in smaller systems these comprise of a wet well, into which the sewage is discharged, and the wet well also houses submersible pumps which pump the sewage to its destination. In a larger station there may be a separate dry well, adjacent to the wet well, which houses the pumps. On some pumping stations the pumps may be housed above ground near the wet well.
In more recent times, a packaged pumping station provides an efficient and economical way of installing a drainage system. They are suitable for mechanical building services collection and pumping of liquids like surface water, wastewater or sewage from areas where drainage by gravity is not possible.
A package pumping station is an integrated system, built in a housing manufactured from strong, impact-resistant polyethylene or GRP (glass-reinforced plastic). The unit is supplied with internal pipework fitted, pre-assembled ready for installation into the ground, after which the submersible pumps and control equipment are fitted. Features may include controls for fully automatic operation; a high-level alarm indication, in the event of pump failure; and possibly a guide-rail/auto-coupling/pedestal system, to permit easy removal of pumps for maintenance/repair.
Compared to the conventional alternative of a concrete well and separate pump system, a packaged system offers the potential for reducing the cost and time involved with civil work and site labour.
Submersible pumps became popular in the early 1960s, when a guide-rail system was developed to lift the submersible pump out of the pump station for repair, and ended the dirty and sometimes dangerous task of sending people into the sewage or wet pit. Growth of the submersible pump for sewage pumping since has been dramatic, as an increasing number of specifiers and developers learned of their advantages.
Submersible pumps are found in many applications, single stage pumps are used for drainage, sewage pumping, general industrial pumping and slurry pumping. They are also popular with aquarium filters. Multiple stage submersible pumps are typically lowered down a borehole and used for water abstraction or in water wells.
A submersible pump is a pump which has a hermetically sealed motor close-coupled to the pump body. The whole assembly is submerged in the fluid to be pumped. The advantage of this type of pump is that it can provide a significant lifting force as it does not rely on external air pressure to lift the fluid.
The generic term ‘Sump Pump’ covers an array of pumping applications where an accumulation of water or other liquids are lifted or removed from a collection pit by utilising a pump. The ‘sump’ can be as simple as rudimentary hollow in the ground or as elaborate as a professionally excavated and constructed concrete pumping chamber.
The liquids to be transferred can be anything from ingress resulting from a surrounding high water table to domestic and industrial sewage and heavy waste materials. High volumes of industrial process water and high temperature boiler condensate water would also be discharged via a ‘sump pump’.
The sump would generally be constructed as a containment to prevent flooding or contamination of local water courses and surrounding urban and rural environments. Effectively lowering the adjacent water table. The actual sumps or pits come in an array of shapes and sizes and are usually a final settlement point in a larger ‘drainage system’. These can be formed by placing concrete rings into an excavation or shuttered and poured concrete; also glass fibre resin (GRP) and moulded polythene underground tanks are common methods of forming convenient sumps. Their function is to form a waterproof collection point where drainage pipes and gulley’s terminate at the sump for final removal or transfer. The further discharge point is most likely to be vertically above the sump position up to a rising main, drainage outfall or soak-away.
The recognised method of removal nowadays would be by using an electric motor driven submersible pump. There are many other methods commonly used for removal of liquids from sumps, one example is; engine driven pumps for situations where no electrical power is available; options are described below.
Removal by ‘sump pump’ can be attained by: