Kilowatts?
- Thread starter Peadee
- Start date
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Why?
But you don't. Once written (and it's old tech now) software is free. Mfrs like to sell something extra that's material, with a clever-sounding name.
Baffling with bu115hit.
Proper control needs a flow sensor, a return sensor, a house sensor, and a (software) clock.
You need a room temp sensor
To close the control loop. WC alone is open loop. The internal house temperature is the thing you're trying to control. It's ridiculous to not have a sensor telling the system what it is.
A rapid change in outside conditions takes time to affect the inside of the house, so WC alone, gets it wrong.
Have a party with 20 people each losing a kilowatt, and WC gets it wrong.
Leave a door open for ten minutes, and WC gets it wrong.
M
mysteryman
You are just posting guesswork and making completely ridiculous statements such as '20 people each losing a kilowatt' and 'leave a door open and WC gets it wrong' and 'in your airtight house you live cheap but die young'.
It is very difficult to make a house completely airtight, and I only ever said 'reasonably airtight'. A door opened for a minute or so does not alter the overall heat loss significantly.
All a properly set up weather compensator needs to know is the actual outside temperature and the desired indoor temperature. By properly set up I mean that the installer has set all the parameters to suit the type of house and heat emitter.
You guys are not helping the OP or contributing in any useful way to the goal of conserving energy.
It is very difficult to make a house completely airtight, and I only ever said 'reasonably airtight'. A door opened for a minute or so does not alter the overall heat loss significantly.
All a properly set up weather compensator needs to know is the actual outside temperature and the desired indoor temperature. By properly set up I mean that the installer has set all the parameters to suit the type of house and heat emitter.
You guys are not helping the OP or contributing in any useful way to the goal of conserving energy.
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Not at all. The outside temperature is NOT the only thing which determines heat loss ina building. People do emit 750 - 1500 watts each. Large modern buildings with lots of office workers don't need any heat at all, they only need cooling, because of the number of people in them.
Am I "Guessing" that people open windows in houses? I can look up and guess that mine is open right now.
Mysteryman I don't suppose you've ever designed and implemented a Control System from its elements in your life. I have, several, including all the software & hardware.
I and others have answered the OP, the discussion has moved on.
Some silly claims have been made about weather compensation, and you can't support them by saying that criticism isn't relevant to the thread.
The objective is not to conserve energy, it's to heat the house right. If you want to conserve energy, turn the heating off. If you want to maximise your profits ny chucking in a cheap and nasty WC system with extra charge for bu115hit, fine.
ANd before you ask if I've installed WC systems, - yes. plenty thanks. If you leave out the inside sensor, they fail to work properly, though the occupier doesn't always notice. They usually turn it up and open a window. I won't have any like that now.
Edit - person radiation figures misremembered. These seem to be authoritative though no source cited:
"...it is possible to generate 11,000 watts of electricity per hour. In fact, different yielded energy levels are 81 watts from a sleeping person, 128 watts from a soldier standing at ease, 163 watts from a walking person, 407 watts from a briskly walking person, 1,048 watts from a long-distance runner, and 1,630 watts from a sprinter."
Less than I stated by x20 is still significant.
I can see the logic in that. Fitting an external sensor, by itself, assumes that the external temperature is the only factor affecting the internal temperature.
I don't know where you get 1kW as the heat loss from a human from. SAP2009 uses a figure of 60W per person for metabolic gains. Other sources suggest up to 100W.
Well, given that the heat lost through wall is proportional to the temperature difference between the inside surface and the outside surface, a sensor on the outside wall is a pretty good indicator. I suspect that most domestic heat is supplied when it is dark, so we can neglect solar heating.
A sudden drop in the external temperature may not mean a sudden drop in the internal temperature. It all depends on the thermal mass of the building.
At the risk of appearing messianic
, a sudden drop in external temperature will set up a thermal wave in the wall. Closed loop control will have no hope of preventing a drop in internal temperature. Only an open loop control factor has a hope of keeping internal temperature constant.Fortunately, in the UK we rarely see large sudden changes in temperature (like 30°C in 3 hours), so our heating has a pretty easy time really.
i don't see the problem here. outside sensor is not to the exclusion of internal controls.
for example my boiler can measure the flow and return temperature, is connected to an opentherm room thermostat which takes information from an outside sensor as well.
there is more then one way to skin a cat and more then one control strategy. as long as the customer is happy then we should be happy
for example my boiler can measure the flow and return temperature, is connected to an opentherm room thermostat which takes information from an outside sensor as well.
there is more then one way to skin a cat and more then one control strategy. as long as the customer is happy then we should be happy
Well fella's,
You've certainly got your teeth well and truly into this thread, bl00dy hell!! A bit technical for me but i'm guessing that I should have a WC to go along with my new boiler, I've gathered that much.
Now, given that I can buy a boiler and the KW's are not an issue, which boiler would you recommend?
I'm thinking "Main" if I want to keep to budget but if I decide to blow the budget, possibly a Viessmann. The choices are endless though really and the problem is, there are no figures anywhere that indicate the reliability of boilers. I feel it's a case of "damned if you do and damned if you don't".
I don't mind paying the extra but what am I getting for the extra outlay?
You've certainly got your teeth well and truly into this thread, bl00dy hell!! A bit technical for me but i'm guessing that I should have a WC to go along with my new boiler, I've gathered that much.
Now, given that I can buy a boiler and the KW's are not an issue, which boiler would you recommend?
I'm thinking "Main" if I want to keep to budget but if I decide to blow the budget, possibly a Viessmann. The choices are endless though really and the problem is, there are no figures anywhere that indicate the reliability of boilers. I feel it's a case of "damned if you do and damned if you don't".
I don't mind paying the extra but what am I getting for the extra outlay?
Back to your original question, eh?
The size boiler you require is determined by the flow rate of the cold water entering the house. You can measure this at the cold water tap in the kitchen using a marked bucket and a watch. Work out how many litres per minute you get.
If you have an outside tap supplied direct from the mains, repeat the experiment with the outside tap full on. This simulates two outlets running at the same time. The smaller the flow difference the better. Remember that all hot and cold water outlets are fed from one source - the incoming old mains. So turning on the washing machine will affect someone in the shower.
Once you know the flow rate, you can work out the boiler size. This will depend on how high you want the water temperature to be at full flow at the lowest incoming temperature. The standard measurement is a 35C rise. So, if the incoming is 10C, the hot water will be 45C, which is more than adequate for a bath or shower. A boiler needs to deliver 2.5kW per litre per minute to give a 35C rise. If you put in a bigger boiler you will not get a faster flow, just hotter water.
This tells you how big the boiler need to be for hot water, but is irrelevant for the heating, which will need much less heat. You can work out what this is by using the Boiler Size Calculator.
When looking at boiler specs you will see that it provided a range of output for heating, e.g 9-27KW. You need to ensure that the lower figure is as far below the calculated requirement as possible, as it then allows the boiler to modulate lower in the warmer weather. This is particularly important if you opt for weather compensation.
If you want to go down the weather compensation route you need a boiler which has W/C capability: Main is not one of them.
Remeha, Vaillant, Viessmann and Worcester Bosch all make good boilers which can take W/C controls.
Right OK
If I don't go for the WC option, are the Main boilers any good. They seem to have been in the market for a long time and each time I mention them, somebody knows somebody with one that's never had a problem. Strangely, I haven't actually spoken to somone that has got one. Only people that know people that have!
I've just had a look at one of these Broag-Remeha Avanta Plus 28c (Combi Boiler) for £758, is it a good boiler and price?
If I don't go for the WC option, are the Main boilers any good. They seem to have been in the market for a long time and each time I mention them, somebody knows somebody with one that's never had a problem. Strangely, I haven't actually spoken to somone that has got one. Only people that know people that have!
I've just had a look at one of these Broag-Remeha Avanta Plus 28c (Combi Boiler) for £758, is it a good boiler and price?
Presumably the price you give is from an online seller. Prices do not include the Flue, which will be at least another £50 depending on how long it needs to be.
Any installer will be able to get it for much less than that, so there's no point buying yourself and then trying to find someone to install it. In any case, if you buy it yourself, you then have the responsibility of taking up any warranty problems direct with the retailer/manufacturer; the installer can, quite legitimately, wash his hands of any problems .
The boilers come with a 5 year parts and 2 year labour warranty. But the heat exchanger has a five year parts and labour warranty. Many installers offer a five year parts and labour warranty on everything. Check this with them.
You have a 24kW boiler and are thinking of a 28kW. Have you measured your flow rate?
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