35 kW heat output HE boiler on 22 mm heating circuits?
- Thread starter Agile
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Its only a system boiler.
It has a 170 li unvented which goes cold during the second shower.
BUT there is no balancing valve on the cylinder ( which would lower the reheat ). There is also an unused pumped secondary loop which is incorrectly connected and would worsen the situation.
If I get the job then I will consider if I should fit a device to enhance the reheat if the heating is on.
Tony
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Hi Tony
Is the proposed boiler not going to be a combi though? Although I see what you mean, even the system boiler will have the same size integral pump.
When you say balancing valve, do you mean the valve before the cylinder to balance the heating and HW input?
I think the proposed boiler is a heat-only, not a combi. This would have no integral pump and would therefore allow for a beefier one to be installed if required.
I have not checked the price yet but the advantage of the show today may have a solution!
Viessmann has introduced a Vitodens 100 as a system boiler with a new power rating of 35 kW !
Interesting it has a Grunfoss 15-70 pump which is a higher power which they say is made just for them! ( Really ? )
It also has a diverter valve for direct use with a cylinder. Dont know yet how it controls the temperature when heating hot water. Hopefully it has a seperate temperature control.
How do others deal with water heating and central heating when different temperatures would be required for optimum operation under weather compensation?
Tony
Viessmann has introduced a Vitodens 100 as a system boiler with a new power rating of 35 kW !
Interesting it has a Grunfoss 15-70 pump which is a higher power which they say is made just for them! ( Really ? )
It also has a diverter valve for direct use with a cylinder. Dont know yet how it controls the temperature when heating hot water. Hopefully it has a seperate temperature control.
How do others deal with water heating and central heating when different temperatures would be required for optimum operation under weather compensation?
Tony
Can't answer that as I didn't go into detail with them about control. I asked about the hw sensor because I know the problems you can get with vaillants when using traditional hot water controls. I know if you use vaillant controls it uses priority hw. Because the cylinder will/should reheat in around 20 mins, the loss in house heating is deemed to be negligible. Always worked ok as far as im aware.
I am sorry my question was not specific enough!
That Viessmann 100 - W has a diverter valve to supply either heating or HW ( but not both! ).
The boiler selects the appropriate sensor for weather comp ( or internal room sensor but they dont tell you that! ) or for HW depending on the demand selected.
My question was aimed at using a standard heat only boiler WITHOUT an internal diverter valve and was in respect of a system using a mid position valve in circumstances when different temperatures are required for each function.
Tony
That Viessmann 100 - W has a diverter valve to supply either heating or HW ( but not both! ).
The boiler selects the appropriate sensor for weather comp ( or internal room sensor but they dont tell you that! ) or for HW depending on the demand selected.
My question was aimed at using a standard heat only boiler WITHOUT an internal diverter valve and was in respect of a system using a mid position valve in circumstances when different temperatures are required for each function.
Tony
If no mixing valve is fitted then the control system should be set up for "Hot Water Priority".
Options like "HW priority" , Shifting priority , and Parallel operation are available with various controllers and hydraulic set ups.
Options like "HW priority" , Shifting priority , and Parallel operation are available with various controllers and hydraulic set ups.
Can someone please help me?
Our house is having a new central heating system installed, with a Viessmann 200W 35kw boiler and a separate unvented Viessmann 250 litre cylinder. The boiler has been installed with 22mm flow and return circuits (2 separate circuits). An outside heating specialist was called in to deal with all the electrical connections, and he says that for a 35kw boiler, these circuits should have a minimum of 28mm flow and return circuits, and ideally 35mm as far as the zone valves. Now both sets of engineers are arguing with each other, and I don't know who is right. The system has not yet been filled, but the installing engineers refuse to upgrade the pipes to 28/35mm.
Who is right?
Our house is having a new central heating system installed, with a Viessmann 200W 35kw boiler and a separate unvented Viessmann 250 litre cylinder. The boiler has been installed with 22mm flow and return circuits (2 separate circuits). An outside heating specialist was called in to deal with all the electrical connections, and he says that for a 35kw boiler, these circuits should have a minimum of 28mm flow and return circuits, and ideally 35mm as far as the zone valves. Now both sets of engineers are arguing with each other, and I don't know who is right. The system has not yet been filled, but the installing engineers refuse to upgrade the pipes to 28/35mm.
Who is right?
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