Condensing Boilers - Assignment Example

Page Condensing Boilers Task The house was built in 1910. This means there are brick walls with poor to no insulation. The windows are alsoold which means that there is a great amount of heat loss through them as well as the passage of cold air into the house in the wintertime. The undeveloped attic space is also not insulated so a lot of heat is lost through there as well. The house has an un-insulated slate tile roof which is a poor retainer of the heat in the house. These are the key components needed to take into consideration when calculating the heating load and size of the condensing boiler needed for this house. The design conditions for this house in southeast England are fairly neutral. There is a temperature variance throughout the year of 25 degrees Celsius. The temperature goes from, on average, 0 degrees Celsius in January up to around 25 degrees Celsius in the peak months of summer. Rainfall remains pretty constant throughout the year, ranging from 45-80 millimeters a month with the summer averages slightly lower than the winter ones. This house has eight rooms that require heat. The room that will require the greatest amount of heat is the living room. The living room is the largest room in the house and also has two windows which, in the wintertime, will be a major source for heat loss in that room. The bedrooms will not have as high of a demand for heat due to the fact that these rooms are smaller in size as well as one the upper level. Heat rises so they are naturally warmer than the downstairs. Bedroom one and bedroom two would require around the same amount of heat due to the fact that they are approximately the same size, in about the same location within the house, they have the same size windows and doorways, as well as the same number of occupants. The heating requirement for each room will vary based upon the size of the room, the location in the house, the number of windows, and the normal occupancy of the room. We will also need to take into consideration the insulation of the walls, ceiling, floors, and windows. Appliances also emit heat, but they are less trivial Page 2 factors when compared to the ones stated above. The heating load calculated is in compliance with the current legislation on energy conservation. There have been laws enacted to help reduce the amount of fuel consumed by homes in England for years now. In 1981 the Energy Conservation Act mandated that certain domestic appliances be labeled as to their fuel efficiency. In 2000 the Warm Homes and Energy Conservation Act was passed and said that Parliament will provide assistance to those who are fuel poor and upgarding to more fuel efficient boilers and other such appliances. The latest and most current is the Energy White Paper (2003). The Paper describes energy efficiency as "the cheapest, cleanest, and safest way of addressing our energy policy objectives" (POSTnote, 2005). This Paper, in theory, will have dramatic potential for carbon savings as well as reduced energy consumption. This Paper describes energy efficiency as the cheapest and safest way to address our energy policy objectives. The downfall to reduced costs of fuel with more energy efficient devices is that some people take the savings as an opportunity to increase their energy usage. If energy is cheaper, then some people can use more of it. This means that energy efficiency will not always produce reduced consumption (Wilhite, 2004). The current legislation has helped to raise public awareness of the problem. Before a lot of the public was unaware and therefore could do nothing to correct it. Now, the public is made to be conscientious of the problem with the Building regulations and Acts passed within the last few years. Part L of the Building Regulations now mandates that any new installation of boilers in England must consist of condensing boilers, unless there are extenuating circumstances. That is not the case with the 1910 traditional mid-terrace house, so we will install a condensing boiler. A condensing boiler is the most efficient boiler on the market converting over 90% of their fuel into heat. They do this by using a heat exchange system to recover heat from the gases in the flue (usually by reducing the temperature). Page 3 Since the condensing boilers are more efficient they do not need to be on as often, saving even more fuel. Another thing we could do to reduce energy consumption is to put blinds in all of the windows. Since the cost to replace the windows would be too great we will compensate by placing horizontal blinds in the windows to reduce the heat loss through the windows. Another method would be to all wall insulation to the house (R 13). This however, is not cost effective. There are proposed incentives that include council tax and stamp duty rebates in exchange for installed efficiency measures. Task 2 The boiler plant will have to be installed. We are using a condensing boiler which will require an additional heat exchanger to cool the exhaust in the flue causing the condensation of the water. This cooling of the exhaust gases accounts for a small portion of the added efficiency of the boiler. The majority of the energy recovered is from the condensation of the water vapor. This releases the latent heat of vaporization of the water. Since the initial boiler was installed in 1910 an endurance test of the existing pipe work must be conducted. Once we are satisfied that the existing pipe work is properly in tact, we need to address to problem of the mildly acidic water that condenses out of the exhaust. The components of the boiler that are in direct contact with the water need to be composed of a corrosion resistant material such as aluminum (or other such metal that can withstand the acidity of the water). A fan is also required to expel the final exhaust from the boiler. The exhaust is expelled from PVC pipe, not the chimney that was required before. We will need to seal off the existing chimney and connect all of the existing pipe work to the new condensing boiler. In order to produce maximal efficiency for the condensing boiler we will also install new, more efficient radiators in the living room (two radiators will need to be installed for this larger room), dining room, kitchen, the upstairs bathroom, and the three bedrooms upstairs. The condensing boiler will contain many sub-assembly parts which can be replaced if they fail. Page 4 Condensing boilers are not the most reliable of heating systems, but they do have the highest energy efficiency rating. Each room equipped with a radiator will have its own individualized thermostat. This thermostat will allow for each room to be heated independently of each other (for how this process works see task 4).The condensing boiler suits the needs of the client, because it complies with current laws and is the most fuel efficient heating system on the market. Task 3 The heating pipe work for this installation must be at least 2 cm in diameter. We will use the existing pipe work, but will install new radiators. We will use one radiator for each room (except hallways) and two radiators for the living room and two for the dining room. We will install one condensing boiler with heat exchanger, flexible tubing, manifolds, and radiant control panel. When installing a condensing boiler low voltage wiring (24v to each individual thermostat) is used. There are specific heat loses and gains for each room which enable us to calculate the u-values for the walls, ceilings, floors, and windows. The exterior of the house is on a concrete slab on top of heavy, compact, moist soil with no insulation below the floor. There is grass in the yard and they house has horizontal blinds hung at a 45 degree angle in every window. The windows are clear, single paned glass with wooden frames. They have no sunscreen shade co- efficient and they have horizontal screens on the bottom half of the outside of the windows. The attic is unvented with no insulation and the front door has a metal polystyrene core with no storm door. The roof pitch is at 30 degrees and also plays a factor in the heat loss and gain of the house. Here are the following results: Roof/ceiling loss/btu gain/btu u-value windows loss/btu gain/btu u-value Bedroom 1 184 162 .032 Bedroom 1 826 338 .9 Bedroom 2 164 145 .032 Bedroom2 826 348 .9 Bedroom 3 126 111 .032 Bedroom 3 826 801 .9 Page 5 Upstairs Bath 90 79 .032 Upstairs Bath 413 169 .9 Upper Hall 81 72 .032 Upper Hall N/A Floors Dining Room 2,295 939 .9 Kitchen 1,137 0 1.358 Kitchen 46 44 .9 Living Room 1,783 0 1.358 Living Room 2,295 985 .9 (front window) Dining Room 1,293 0 1.358 2,295 2,524 .9 (side window) Downstairs Bath 0 0 1.358 Front Door 301 191 .35 Downstairs Hall 796 0 1.358 Walls loss/btu gain/btu u-value walls loss/btu gain/btu/ u-value Bed 1 (front) 365 190 .091 Dining (front) 201 105 .091 Bed 1 (left) 404 210 .091 Dining (right) 418 217 .091 Bed 2 (back) 365 190 .091 Hall (front) 525 273 .091 Bed 2 (left) 360 187 .091 Kitchen (back) 434 225 .091 Bed 3 (back) 360 187 .091 Kitchen(right) 311 162 .091 Bed 3 (right) 262 136 .091 Living (front) 365 190 .091 Up Bath(front) 248 129 .091 Living (left) 346 180 .091 Up bath (right)305 158 .091 Up Hall (front) 290 151 .091 Using the above numbers the total heat load for the house is calculated at 84,845/btu. The total latent gain is 5,900/btu and the total sensible gain is 18,180/btu. Task 4 There will be individual thermostats in every heated room in the house. All of the smaller rooms will have one radiator, because a single radiator will be enough to heat the smaller area. The larger rooms, like the living room, will need two radiators. The thermostats in every room will provide a zone system when one or more rooms drop below the designated temperature for that room. The control Page 6 panel has the two thermostat wires hooked up to the corresponding zone valves for each room. The zone valves open up when the room temperature drops below the level on the thermostat. For example, the kitchen could be zone one. When the kitchen temperature drops below the temperature on the thermostat, the radiant control panel only calls for heat to that one zone. This opens the corresponding valve allowing hot water to pass thru while the rest of the house and valves remain closed maintaining their individual, designated temperatures for those rooms. This is another reason the condensing boiler is so efficient. As mentioned before there are certain materials used in the installation of the condensing boiler due to the acidity of the water in the system. All parts of the heat exchanger and any other part likely to come into contact with the acidic condensate produced by the boiler should be adequately corrosion resistant. This will help add to the longevity of the boiler. Maintenance of the boiler is essential. A water treatment should be provided if there is harsh water as well as pump protection (automatically starts pump for a few seconds if the boiler is not being used and prevents seizure). If there is build up of sludge or other such material it can be removed with certain chemicals or a flush. The condensate drainage should be installed with a slope of at least 2.5 degrees. The boiler's sub- assemblies can be replaced if they fail, but most manufactures do not provide information on reliability or component performance. POSTnote (2005) Parlimentary Office of Science and Technology. Number 249. Wilhite, H.& Nogard, J. (2004) Equating efficiency with reduction: a self-decption in energy policy. Energy Env. 15, 991-1009. Read More