Hi guys, I hope someone can help as I just don’t understand what I’m looking at. I am installing a new central heating system, it is for a holiday let with 3 beds and 2 baths over 4 floors if it makes any difference. I have chosen a boiler, the Viessmann Vitodens 200W 35kW Combi Boiler Wb2B297, I believe this to be the top of the range so should easily handle it. The bit I’m stuck on is this, the top room has lots of roof lights so ends up in a situation where either that room is red hot where the rest of the house is freezing or the other way round depending on the weather. What I want to do is have 3 zones independent of each other, so if the a floor needs heat but the other 2 don’t, the heating will come on but only for the floor that needs heat. Is this possible and how would I do it? Thanks in advance guys.
independant floor control
- Thread starter phillippilkington300
- Start date
How do you expect a 35 kW combi to supply two baths at the same time?
I would say that UFH is the last type of heating to have for holiday lets! It has a very long thermal time constant and is exactly the opposite of what people on holiday want.
Presumably you know much more about specifying heating systems than your registered installer?
Tony
would it not be easier and more economic to have one zone, with a central location for the roomstat (in the living area) and have TRV's in the other rooms? that way if the top floor is red hot, the TRV's will close and allow the rest of the house to still heat up until the temp setpoint is achieved everywhere else?
what you want is possible, but you will need 3 seperate room stats controlling 3 different zone valves,so when one floor is calling for heat,it will only open the corresponding zone valve to that floor.
what you want is possible, but you will need 3 seperate room stats controlling 3 different zone valves,so when one floor is calling for heat,it will only open the corresponding zone valve to that floor.
And how is that less economic in this situation than having one mahoosive zone with large variances in temperature?
over 150m you need two zones anyway.
Using the TRVs to control the temps in each room seemed too easy and would obviously do the trick anyway.
So I had concluded that he has under floor heating which does give a ( severe ) control problem.
But you may well be right! He seems to want to specify everything himself without taking advice from his experienced and qualified (?) installer. So it may well be that his obvious lack of understanding of the subject may have caused him to fail to realise that TRVs on radiators will do exactly what he needs.
Tony
So I had concluded that he has under floor heating which does give a ( severe ) control problem.
But you may well be right! He seems to want to specify everything himself without taking advice from his experienced and qualified (?) installer. So it may well be that his obvious lack of understanding of the subject may have caused him to fail to realise that TRVs on radiators will do exactly what he needs.
Tony
Tony, there is no need to be so rude to everybody, you have clearly had a bad day. I may have chosen the boiler, I will re look at that. I do want the advice of an installer but I like to know what they’re talking about which is what this forum is for isn’t it? They also all say different things as opinions change, I have had 10 different boilers recommended to me for a start. I do not have under floor heating either. Thank you guys, that is helpful information, I had heard that before but didn’t know what they did, I understand a little better now.
my old house was over 4 floors and 3 beds, 2 baths, but it wasnt a mansion. it only had 10 radiators.... a normal system with TRV's and room stat worked well. without knowing the extent of the size of this house i was just offering what advice i coudld. I merely meant that having 3 different zones would mean buying more valves etc...so less economic
I have had a wonderful day! Car would not start after refuelling but I was so lucky because this very helpful Scottish fellow gave me a lift home so that I could take another car and use it to restart the original. Only an alternator belt failed so a very cheap and simple repair.
I dont see that I was rude to you or anyone else. I just pointed out that your obvious lack of knowledge has drawn you to come to totally inappropriate solutions.
Instead of explaining your requirements, you boldly tell us that you have chosen a particular boiler as if you already have had it installed. Far better to have asked for solutions.
I realise that, like many others, you probably think that anyone who installs boilers are plumbers, and that all plumbers are by definition are thick. But be aware that most of those who have commented here have degrees.
Tony
I dont see that I was rude to you or anyone else. I just pointed out that your obvious lack of knowledge has drawn you to come to totally inappropriate solutions.
Instead of explaining your requirements, you boldly tell us that you have chosen a particular boiler as if you already have had it installed. Far better to have asked for solutions.
I realise that, like many others, you probably think that anyone who installs boilers are plumbers, and that all plumbers are by definition are thick. But be aware that most of those who have commented here have degrees.
Tony
Was your boiler sufficient then? Do you know what it was? I have looked at boilers since Tonys post, and the 35 kw combi seem to be top of the range of all of the manufacturers without going industrial, it is also what the sites recommend for my setup.
Tony, I do not think plumbers are thick, I happen to be an engineer myself so please don’t make assumptions about me. You have been rude, I was asking about the solution to my problem and supplied the other information encase someone said, hey, you don’t want that mate, have a look at this. Where I trained that is called setting a scenario, perhaps they didn’t cover that on any of your courses. I am great full for the advice, just no need to be like that. Your attitude is exactly why people are the way they are to us technicians.
Tony, I do not think plumbers are thick, I happen to be an engineer myself so please don’t make assumptions about me. You have been rude, I was asking about the solution to my problem and supplied the other information encase someone said, hey, you don’t want that mate, have a look at this. Where I trained that is called setting a scenario, perhaps they didn’t cover that on any of your courses. I am great full for the advice, just no need to be like that. Your attitude is exactly why people are the way they are to us technicians.
If you want to fill two baths at the same time then you need stored hot water which can supply up to 30-40 litres per minute if everything else is suitable.
A combi can supply up to about 14 li/min. Enough for one good shower or two lower flow rate showers.
A bath user expects it to fill in about 4 minutes which needs a flow rate of about 20 li/min.
Tony
A combi can supply up to about 14 li/min. Enough for one good shower or two lower flow rate showers.
A bath user expects it to fill in about 4 minutes which needs a flow rate of about 20 li/min.
Tony
Thank you, that is helpful and useful information, I would expect people would be ok with only using one bath at a time, there is only one shower in the property. Would you say that the boiler I mentioned is suitable then?
It is not up to me to say if it will be suitable, only to point out the short comings of a combi which can only properly supply ONE hot outlet at a time.
Even that depends on the dynamic flow rate available from the mains. You will need a minimum of about 15 li/min @ 1.0 Bar.
That boiler will give about 14 li/min which will fill a bath in about 5-8 min which is not as fast as a stored supply but still reasonably fast.
As long as you accept that only one bath can be filled at a time AND that anyone filling a bath will disturb anyone taking a shower then that boiler will be suitable with these restrictions.
There is also the problem of the pressure to the upper floors. You need a higher dynamic flow rate pressure if using hot water on the upper floors.
Also realise using water on lower floors may starve the upper floors. Before specifying any combi, the dynamic flow rate needs to be measured and assessed.
Tony
Even that depends on the dynamic flow rate available from the mains. You will need a minimum of about 15 li/min @ 1.0 Bar.
That boiler will give about 14 li/min which will fill a bath in about 5-8 min which is not as fast as a stored supply but still reasonably fast.
As long as you accept that only one bath can be filled at a time AND that anyone filling a bath will disturb anyone taking a shower then that boiler will be suitable with these restrictions.
There is also the problem of the pressure to the upper floors. You need a higher dynamic flow rate pressure if using hot water on the upper floors.
Also realise using water on lower floors may starve the upper floors. Before specifying any combi, the dynamic flow rate needs to be measured and assessed.
Tony
phillippilkington300
While I agree that TRV should be fitted to all rads, remember that they do not control the boiler.
You say that the top room suffers extremes of temp.
So say very cold night room stat on middle floor set at say 20deg, heating comes on, middle floor reaches 20deg, room stat shuts heating system down, top room is still cold because middle floor is at set temp.
I would say the only way to heat all floors is to split it into 3 zones with a room stat and zone valve on each floor.
No TRV in the room with the room stats, but fitted to all other rads,
With this system the top room can have heating on without the other floors being heated or the other way round no heating to top floor but heating on the middle floor or bottom floor or both,
You could have one programmer controlling the whole house or have three separate clocks, for total control of each floor.
David.
While I agree that TRV should be fitted to all rads, remember that they do not control the boiler.
You say that the top room suffers extremes of temp.
So say very cold night room stat on middle floor set at say 20deg, heating comes on, middle floor reaches 20deg, room stat shuts heating system down, top room is still cold because middle floor is at set temp.
I would say the only way to heat all floors is to split it into 3 zones with a room stat and zone valve on each floor.
No TRV in the room with the room stats, but fitted to all other rads,
With this system the top room can have heating on without the other floors being heated or the other way round no heating to top floor but heating on the middle floor or bottom floor or both,
You could have one programmer controlling the whole house or have three separate clocks, for total control of each floor.
David.
Ah, that is what I was asking, so is there a special control unit for that or is it just down to the heating engineer to set it up correctly? As you say, its ok having the top rad turn off if too hot, but if that room is the cold one, I need it to know to come on. This is my reason for asking on the forum. Had I just turned to a heating company I could very well have ended up with the wrong setup.
I avoid this situation in my home by using a wireless roomstat. If im going to be downstairs i take it with me to the living room. If downstairs is very warm due to cooking, plasma being on, and people congregating in the living room, i take the stat upstairs when i go, so i know that it will call for heat when i need it, and the TRV's will be closed downstairs.
However i can see that in a holiday home, paying guests will not want to have to do that.
Using this method has saved me quite a bit of cash over the winter months.
However i can see that in a holiday home, paying guests will not want to have to do that.
Using this method has saved me quite a bit of cash over the winter months.
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