Patent Application
20110284646
The present invention relates to a thermostatic device, which is designed to accelerate the heating process in instant water heaters to reduce heating costs and save significant amounts of water and carbon emissions
In homes where a combination boiler is fitted, when a hot tap is used, there is always a delay while the boiler warms itself up to warm the cold water passing through it, to service the hot tap. The time delay in getting hot water from the tap depends on
The object of the invention is to provide a thermostatic device which, when connected to the hot water outlet of an instant water heater/combi-boiler, reduces the time for hot water to be outlet and provides an energy and water saving.
According to the present invention there is provided a valve comprising a valve body having a fluid inlet and a fluid outlet and having a thermostatic valve assembly located in the flow path from the fluid inlet to the fluid outlet, wherein the thermostatic valve assembly is supported in a guide tube and is biased into a normal closed position, the thermostatic valve assembly including an actuator member and a valve member, which is displaced by the actuator member, as the temperature of the fluid entering the valve increases, characterised by a trickle bore, or a bypass channel restricting flow of fluid through the valve until the fluid achieves a predetermined operating temperature.
The thermostatic device of the present invention is intended to be readily installed on the hot outlet pipe of an instant water heater or a shower heater. The device, being thermostatic, reduces the maximum flow from the combination boiler/shower heater to about a third of its capability. This causes the water to heat up more rapidly as it will be retained in contact with the heater element for longer. Once the water temperature has increased sufficiently to the temperature set on the thermostatic device (around 35° C. to 40° C., which is adjustable), the thermostatic characteristics of the device causes an internal valve to open and increase the flow rate to the maximum capability of the appliance. In tests, the device enabled the water temperature to increase to 40° C. within 45 seconds, saving energy, water and time, whenever the tap or shower is turned on. Another benefit of this device is that it can be set to maintain a minimum outlet temperature, so that, for example, a bath could be filled just using the hot tap and depending on the time of year, it will automatically adjust the flow to maintain the set outlet temperature even though the incoming temperature to the boiler may vary by 2-30 degrees.
According to the applicants own tests, the following carbon savings and water savings were typically found.
Firstly, “Boilers account for around 60% of the carbon dioxide emissions in a gas heated home” (Energy Saving Trust)
The following example illustrates carbon savings through having a valve according to the invention fitted on one domestic dwelling on a sample household of four. The formula is sourced from The Carbon Trust.
A 28 kw combination boiler uses 30 kw of gas per hour.
Average cost of gas is around £0.05 per kilo watt (at the time of writing).
Therefore, 30 kw×5 pence is £1.50 of gas used in one hour by the boiler.
Or 2.5 pence per minute, and 1.25 pence in 30 seconds.
A valve according to the invention could save the household 30 seconds wait time for hot tap water. In 30 seconds the boiler would have used 0.25 kw (250 watts).
If our sample family of 4 used the tap 10 times a day each, that is 40 tap turns×250 watts=10 Kw of gas saved.
Multiply that by one year and you get 3,650 Kw of gas saved @ £0.05 per Kw—£182.50 saved per year.
Using the CO2 formula below from Carbon Trust
http://www.carbontrust.co.uk/resource/conversion factors/default.htm
Also from the Carbon Trust are the carbon emissions of water use as calculated by the UK water industry.
If large amounts of water are used, it makes sense to include the carbon emissions of water in carbon footprint calculations. A summary of the figures is given below:
Water supplied:
To supply 1 mega litre of water produces 0.276 tonnes of CO2 emissions. This works out at 0.276 kg CO2 per cubic metre of water supplied.
The carbon savings on water after fitting a valve according to the invention worked out at 0.003 tonnes per year p.a. per home.
Assume 6 litres of water are saved each time the hot tap is used. Water costs approx 0.3 p per litre and therefore the cost of 6 litres is around £0.02. Using the same scenario as above for a family of four using the tap 10 times a day each, the savings=£0.80 per day from a saving of 240 litres of water per day. Multiply this by one year to provide savings on the cost of water of around £292 per annum
Volume of water used—87,600 litres (87.6 cubic metres) saving per year, per family of 4.
But there are many variations, e.g: type of boiler; whether the heating is on at the same time; when was the boiler was last used.
Further tests have been carried out on the valve (termed “CombiSave”) by independent energy consultants, which carried out in a typical domestic environment, but in a controlled manner, the test regime being based around the following standard—BS EN 13203-2:2006
Gas-fired domestic appliances producing hot water—Appliances not exceeding 70 kW heat input and 300 L water storage capacity.
Within this standard there are regimes to describe what constitutes a ‘type of delivery’, when that delivery becomes useful, and how much energy must be delivered when the delivery has become useful.—See Table 1, below.
For a ‘basin’ type draw off the volume and energy were measured until the temperature for useful energy is required. From this point, the volume to deliver the required energy for this type of draw off was measured.
For a ‘continuous flow’ draw-off such as a bath, just the total volume drawn-off to deliver the required energy for this type of delivery was measured.
Each type of draw-off was conducted in both DHW only, and DHW and central heating modes. In DHW mode, for each draw-off the boiler was returned to a base temperature by running mains water through the boiler with the boiler switched off.
To measure the volume and energy, a compact magnetic flowmeter in combination with rapid response thermocouples were used. The flowmeter provides instantaneous flow rates and the data logger was set to record every second.
Energy and volume values were then calculated from the recorded data.
The results of these tests are set out in the table below.
The 15 and 30 are the temperature increase of the water not its temperature the increase) With central heating turned on or off.
The water flow rate is indicated in litres per minute
Volume is the water runoff before temperature increase is reached
Energy is the gas used before temperature increase is reached.
The valve of the invention can be manufactured with a 45 degree inlet pipe, which could be in a fixed position with a push fit type of pipe connector. The outlet of the valve could have a union type fitting, in which to attach an angled type of push fit connector which could also be angled at 45 degrees. This would enable the valve by rotating the outlet through 180 degrees to be installed on a straight line of pipe or to cut out an elbow joint and fit with a 90 degree outlet.
The design of this is to cut down on the requirement of further fittings and also to make it a DIY fit, retailing it in a blister pack with a simple pipe cutting device being sold with it.
A smaller version of the valve can also be utilised for electric showers, where the flow rate is a lot less than a combination boiler. It would still be fitted with its variable bypass but is designed to be fitted inline by the customer. The inlet and outlet would be fitted with a standard male and female shower connector. The existing shower hose will need to be unscrewed from the heater unit and the valve fitted direct on to the heater unit with the hose being re-attached to the new valve. The valve could be finished in chrome, or have chrome-finish plastic cover, so it can be more aesthetically pleasing. This also could be a DIY fit.
The electric shower version will restrict the flow rate on initial start up and will fully open to let the water flow unrestricted once the water has reached its desired minimum temperature, thus saving water and electric by shortening the warm up time to enable a person to enter the shower earlier. Savings on electric, water and carbon are as follows: based on a family of four each showering once per day for 350 days a year would equate to a saving of around to 77 Kilo Watts of electricity, 1,400 litres of water this equates to a carbon saving of 41 Kg.
The valve is also ideally suited to be fitted during the manufacture of a combi-boiler. So as to give the end user a choice of running their hot water with or without the use of the valve, a three-port valve could be fitted ahead of the device so that the water could be diverted around in a bypass. This valve could be controlled by hand with a ¼ turn mechanism. This could help increase the sales of boilers for the manufactures as they would be able to claim higher fuel efficiency and lower carbon emissions.
The present invention will now be described by way of example with reference to the accompanying drawings, in which:
Referring firstly to
Within the valve body 10, a spring-biased thermostatic piston assembly 13, located within a guide tube 18, is positioned in the flow path. The thermostatic piston assembly 13 includes an actuator 14, and a cylindrical valve member 15, which, when cold, is biased by a spring 16, acting on the guide tube 18, into a sealing engagement with the valve headset 17. A tickle bore 19 is provided in the cylindrical valve member 15 proximate the inlet 11 to enable water to initially trickle flow through the piston assembly 13.
When a hot water tap is turned on, water will start to flow from the boiler through the bore 19 from the boiler to the tap. The bore is preferably a 2 mm hole, but can be sized as required according to system requirements. Owing to the size of the bore 19, the water flow is reduced to approximately 2 litres per minute, which is sufficient to trip the mechanism to fire up the boiler. The temperature of the water flowing through the is cold initially, unless it had recently just been used Within the boiler, a contained predetermined amount of water is heated, which indirectly heats the cold mains water passing through through the boiler to the tap via the thermostatic valve 1. Due to the restriction of the 2 mm bore 19 in the valvemember 15, the heat is not removed from the boiler as quickly as it would be the case if it were allowed to flow freely, unhindered to the tap as with conventional arrangements. This flow restriction causes the boiler to warm up to its set operating temperature more quickly, using less gas and water. In some boilers tested, 50 degrees centigrade was achieved 40 seconds more quickly than previously.
As the cold water from the boiler starts to warm it passes through the bore 19 in the thermostatic piston assembly 13 passing over the actuator 14. The actuator 14, which typically may be a plastics material rod including a wax plug, or a copper rod, which expands, pushing against the variable headset 17 at one end, and the base of the guide tube 18 against the action of the spring 16. This causes the piston seal to lift, allowing the water to flow pass the seal up to the boilers operating flow rate. When the tap is turned off, the boiler will shut down and the thermostatic piston assembly 13 contracts as the temperature of the water around it decreases. The desired water temperature of the outlet can be adjusted and preset with the variable headset 20 by screwing it up or down.
| Number | Date | Country | Kind |
|---|---|---|---|
| 0900866.5 | Jan 2009 | GB | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/GB2010/050049 | 1/14/2010 | WO | 00 | 8/6/2011 |
