Thirteenth lunar month of central heatingTwelfth lunar month of central heatingEleventh lunar month of central heatingEvaluation: a year from installationTenth lunar month of central heatingIndex
Second lunar month of central heating
by Unknown - 12:43 on 05 November 2013
Second Month
If you are a newcomer to this blog, it might be best to begin by reading earlier instalments of the blog, perhaps starting from "Why we installed a Smart".
| Total kg pellets used | 734kg |
| Average daily kg | 26.21kg |
| Metered kilowatt hours to central heating/hot water | 1897wh |
| Gross kilowatt hour value of pellets | 3523.2kwh |
| Space heating lower bound | 678.18kwh |
| Space heating including residual heat | 1047.22kwh |
| Space heating including residual heat and further ESBE distortion | 1116.9kwh |
| Efficiency at lower bound | 73% |
| Efficiency including residual heat | 84% |
| Efficiency including residual heat and further ESB distortion | 86% |
| Cost of pellets | £150.10 |
| Potential RHI subsidy | £254.58 |
During this month, we began by running the Smart at a maximum output level of 3, then after about a week we switched to 4, and finally a couple of days before the end of the month we had two sessions of 6.30 to 10.30 then 12.30 to 22.30 instead of our previous 6.30 to 10.30 then 16.30 to 22.30. We were happy with the Smart's performance throughout.
The following notes are for anyone who wants a technical explanation of the table.
- Using the metered output to the central heating system I can try to calculate the amount of heat that goes to space heating and thereby calculate the efficiency of the Smart 120. The "lower bound" figure is calculated on the basis of Klover's published ratios between output to central heating/hot water and output to space heating for different levels of output.
- So why do I give other figures in addition to the "lower bound"? I do this because we have an ESBE valve fitted in our system which enables the Smart 120 to heat up quickly by preventing hot water being circulated to the central heating until the Smart has heated up. It does not let water circulate to central heating until the water temperature is 60C and then it progressively lets more through until at 70C it is fully open (see the links section for further information). This means that Klover's standard ratios between space heating and central heating do not apply until the Smart 120 has heated up. Even when it has heated up, if the water temperature keeps dropping below 70C (as it does frequently in our set up), then Klover's standard ratios do not apply. The figures which include "residual heat" allow for the effect of the ESBE valve in the heating up phase. The figures which, in addition, include "further ESBE distortion" allow for the variation in ratio between space heating and central heating that occurs because of the water temperature fluctuating below 70C. I do not think my calculation of these figures is definitive, but they are my best attempt to calculate the Smart's efficiency in the installation we have in our house. The calculation of residual heat is based on measurement and science-based calculation. The "further ESB distortion" figure is more of an estimate.
- If you read earlier items in the blog, then you will see that my attempts to estimate the Smart's efficiency have been criticised.
- Before putting up this month's figures, I made an attempt to measure what happens in the Smart's initial heating phase. I did this with only a small sub-circuit of our central heating open, so the Smart would heat up rapidly (and I would not have to hang around watching it for too long). For convenience, I made my measurements after it had been switched off for 2.5 hours, so it was heating up from lukewarm rather than from cold. It took 10 minutes for the Smart to light its pellets and then to increase its burn until it reached an output level of 4 (I had set this to be its maximum output level). It took a further 21 minutes to reach 70C. If the Smart had been performing in line with Klover's published figures it should have output 4.99 kilowatt hours to the central heating/hot water and about 1.782 kilowatt hours to space heating. But I measured 2.29 kilowatt hours to the central heating and 4.9 kilowatt hours to the stove. This reversal between distribution to space heating and central heating illustrates how the proportions of Smart's output to central heating and space heating are radically altered by the ESBE valve when the Smart's water temperature is below 70C.
Add your comment
Please note that whenever you submit something which may be publicly shown on a website you should take care not to make any statements which could be considered defamatory to any person or organisation.
Roger's comment: As I understand it, the ESBE load valve is not recommended by Klover. Nor was it the installer's own idea. It was installed because Stovesonline/Firepower Heating who distribute Klover in the UK recommended it to the installer. They are used to it because it, or its equivalent, is a standard modern fitting with traditional wood-burning boiler stoves. A plus point of it is that it enables the stove to heat up relatively quickly for cooking. A downside is that it reduces input to the central heating system. To escape this reduction as much as possible, I have set the target winter water temperature on the Smart to 75C instead of the default 70C. With the default target, the Smart would reduce from output 5 at 66C, to 4 at 67C stepping down to 1 at 70C. Since the standard ESBE valve is only fully open at 70, with the default target water temperature, the Smart would never provide its full output to the cental heating. I am considering whether we should ask for the standard thermostat in the valve to be replaced with one that will cause the valve to be fully open at 65C. As for the programmer, we use it to set output levels and to set the target water temperature. It is certainly effective for these purposes, but for standard central heating purposes we use our pre-existing house programmer.