OPTIONS for Replacing Boiler Plant Report to Tenants Sussex Lodge London W2 & 16 Stanhope Terrace London W2 BPME Consulting Engineers Tel: 01932 873 653 13 JULY 2003.
Replacing Boiler Plant... 1 1. Existing boilers and associated plant... 3 2. Installation of new gas fired high efficiency boilers... 4 3. Risers... 5 4. Options... 5 4.1. Notes regarding option A... 6 5. Recommendation... 6 Page 2 of 7
1. Existing boilers and associated plant There are several serious problems concerning the existing boilers and distribution systems. Of the originally installed four oil fired boilers, only two are now capable of operating and one of the remaining two is now leaking. Due to the age of the plant it will not be possible to repair the boilers and on failure, which could happen at any time, the building will be without any heat. The existing boiler plant has a probable efficiency of less than 50% compared to modern condensing gas fired units at 95%. The hot water is currently being produced from an external rented oil fired unit which was originally intended as a temporary measure until the boilers were replaced, this unit is expensive at approximately 2,000.00 per month and has been installed without planning permission. The existing boiler room plant and basement pipework are both insulated with asbestos, making any repairs that become necessary very expensive. The existing hot water distribution is by means of galvanised pipework and fittings. Since the temporary hot water unit is connected to the main system by means of un-insulated copper pipework corrosion has occurred ( mixing copper and galvanised causes de-zincification ), probably throughout the building to the hot water system, this is now beginning to manifest itself as leaks. Such leaks will become more frequent in the near future. The services to the building are all in very poor condition and careful consideration should be given to a total renewal carried out in phases over a period. Replacement of the boilers, asbestos removal and the replacement of the hot water distribution system is critically urgent. To reduce funding requirements several programs of work over varying periods have been studied. This report outlines the various options that have been considered. Unless a total renewal of the hot water system is considered now, to reduce future corrosion to the remaining old system it is necessary to install new galvanised pipework (same as existing) and then replace this with copper when the total system is proceeded with. Obviously this is not financial sense, but if funds are not immediately available is the only way forward. The costs of the options do not include for the renewal of the hot water distribution system and assume galvanised pipe work. I should also mention the earlier discussions in connection with the provision of individual heating systems to the flats. This was rejected for a number of reasons. Page 3 of 7
First, the smaller flats have little room to include such a system. Secondly, the installation of such a system would require new pipework within the flats and possibly new gas distribution in the block. Thirdly, the running costs of a new boiler should be no more that the costs of individual systems. More importantly, centrally provided constant hot water should be provided in a luxury block which Sussex Lodge will eventually become. 2. Installation of new gas fired high efficiency boilers It is not possible to install a mix of new gas and old oil fired boilers working into a common chimney stack such as exists at Sussex Lodge. Large boilers require separate flues discharging at roof ridge level. Flues from new gas fired boilers cannot be installed within the existing brick chimney stack whilst the existing oil fired boilers are in use, or available for use. Small boilers at about 50 kw each could be installed with simple flue pipes protruding through the wall at low level to atmosphere. Some modern larger boilers consist of several 50 kw modules built into one frame. By separating the modules, each would be considered separate boilers which would permit low level flue outlets. In this case no scaffolding or expensive flue liners would be required. These boilers form a considerable plume. The existing boiler plant is rated at 1,100 kw but the actual duty now required is approximately 650 kw (by using modern techniques especially for hot water generation) if all flats are occupied. Normally 40% of the flats are unoccupied. During these periods, and provided the heating is turned down to frost protection level, 400 kw is adequate. The boiler capacity required will be further reduced as the remaining flats in the block replace their original Crittall steel windows with double glazed units. A totally new modern high efficiency installation created in the garage, clearing the existing boiler room installation and basement asbestos will cost approximately 200,000 if arranged as one contract to be carried out during one summer. To match the varying load, a final scheme incorporating 3 boilers rated at 220 kw each is to be preferred. The temporary boiler is expensive and unsightly. The remaining two existing boilers could fail at any time. Repairing them may not be possible. I have also been asked to report on the possibility of a phased installation. Sensibly there are four possible alternative ways forward: Page 4 of 7
To help cash flow it is possible to install 1, and then 2 and finally the 3rd boiler on a phased basis backing up with the old oil boilers in the early stage. Using temporary smaller connecting pipes until phase 3 would also reduce the expenditure in the first year but cost more in total. 3. Risers The existing risers date back to the construction of the building and are uninsulated. They are galvanised iron. They need to be replaced with new copper risers at the same time as or shortly after the boilers because the distribution system in the garages will be in copper. This will allow copper piping to be used throughout the block as the plumbing systems within the flats is renewed over a period. However, this will require the plumbing replacement program to be carried out over the very near future as otherwise the new copper distribution in the garage and the copper risers would cause further damage to the old galvanised system (see separate specification). The cost of this has not been included in this specification and will be the subject of a further report. 4. Options A ( 1 ) Wait until the heating season is over and install one 220kW boiler in the garage area and connect into old system in the boiler room such that the old boilers can also be used in the coldest weather. Four new 3 diameter flues would have to temporarily run to roof level on the OUTSIDE of the existing brick stack in order to be able to use the oil fired boilers when necessary. cost 77,000 A ( 2 ) As above but install 2 boilers now ( 440 kw ) cost 98,000 see further notes regarding this option B Wait until the heating season is over and install 3 new boilers (giving 660 kw) in the existing boiler room with new flues within the existing brick stack This would require the full duty to be installed now but could use old pumps, valves pipes etc.(not recommended ) cost 128,000 C Wait until heating season is over and install 3 new boilers in Garage area to enable existing boiler room to be cleared for other uses (cost of clearing not included). Flues can be installed inside the brick chimney stack. Page 5 of 7
This would require new pumps and valves (recommended subject to cash availability) cost 156,000 D Install a series of smaller wall hung boilers in garage area, local low level flues. These flues will produce a considerable plume. This would permit, say, 50% of the final required duty to be installed now, temporarily retaining old oil fired boilers which could be brought onto line in the coldest weather. cost 94,000 All of these prices include removing only sufficient asbestos for the work to be undertaken, the new gas supply and design costs. Items A, C & D will require an enclosure to be built from brick or plaster board and studding with a steel barrier to prevent damage by cars. I have not costed this. A further means of escape may be necessary from the basement. All prices include a very high efficiency hot water generating plate heat exchanger 4.1. Notes regarding option A The cost of option A1 at 77,000 (1x220 kw boiler) has been achieved by temporary connections into the old system and using smaller pipes and equipment than will be required for the final scheme. Some 17,000 would be wasted in the longer term, for example, 1 emergency fire gas shut off valves have been allowed initially instead of the 4 that will finally be required when the further two necessary boilers are installed, the 1 being discarded later. Four (or 8) 3 (75mm) flues on the outside of the chimney stack may require planning permission although it should be possible to obtain a temporary structure licence. If, say, 20% of flats are un-occupied, hence not requiring showering or baths and with the central heating turned down, 440 kw will be sufficient for the winter without the need to operate the old oil boilers. This would allow the flues to be placed inside the brick stack and avoid the cost of changing them later. Option A2 is based on installing small pipes for just 2 boilers and changing them to larger when the third boiler is installed. It would of course be more sensible to install the pipework and pumps now sized for the final project even if only two boilers were installed but this will cost a further 33,000 in the first phase, but giving a lower total at the completion of installing the 3rd boiler (160,000 instead of 167,000). This 2 boiler scheme is a gamble on weather and occupancy. 5. Recommendation If finance permits it, I strongly recommend that a total new system is installed now as a single capital expenditure of around 200,000. If spread equally over 45 flats (in fact, the charges would be shared according to the service charge proportions) this figure equates to 4,270 per flat. The block s fuel bill should drop from around 41,000 pa to nearer 14,000 pa and there will also be a saving of around 18,000 Page 6 of 7
pa in boiler rental and maintenance costs. The annual savings for the block should be of the order of 45,000, which indicates a 4 ½ year payback to give a reliable new plant. The payback would be shorter if controlled valves were installed to enable heating to be switched down to trickle for unoccupied flats. There are significant advantages to building a new plant room in the garages. The installation in a custom built area will be much simpler than if the installation had to take place alongside existing plant whish is still in use. Changeover will be effected in 1-2 days causing minimum inconvenience to tenants. In addition, asbestos would need to be removed from the existing boiler plant room before these works were undertaken. If it is absolutely necessary to reduce immediate expenditure as much as possible, I would recommend option A2, but delay fitting the second boiler until further funds are available perhaps November or December. This would give a contract commitment of some 79,000 but also allow the fitting of the second boiler at a further cost of 19,000 in the winter, and then a third at some future date if occupancy demanded it. Page 7 of 7