Your opinions on this Heating Diagram Please

[gorty]

[Please see diagram nearest the bottom of thread]

This diagram represents what i'd like to install to my poorly insulated 1890s 3-bed semi in chilly scotland, boiler and tank will be in ajoining garage. I'd like to program ON/OFF times for Zone1, Zone2, DHW, upstairs towel rail and Underfloor. All comments welcome, in particular what controls and boiler brands should I explore? Note the towel rail has it's own programmer as nearly all the main brand programmers only do 2 zones and DHW. Do you see any problem in mixing the underfloor with rads in this way? Compatibility-wise, am I correct in assuming any programmer could potentially be used to switch any zone valve and any boiler? i'm also assuming the underfloor programmer will allow me to time each underfloor section individually, is this correct?

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• gorty
• 27 Jan 2011
• 1

 

[misterdubya]

Bit unsure about the u/f heating return pipe.

Mr. W.

 

[AlanE]

Bit unsure about the u/f heating return pipe.

That should tee into the radiator heating return PRIOR to the cylinder Tee to prevent secondary circulation.

Cylinder Tee should always be the last before the boiler.

 

[misterdubya]

I was wondering about reverse circulation, but I'm no expert in u/f heating so wasn't sure if it could actually occur if the system was plumbed in 'as per the diagram'.

Mr. W.

 

[gorty]

the diagram is intended to show functionality, not the actual pumbing. although I'd be as well redrawing with the plumbing shown accurately. Is this diagram enough information to ask for a quote on materials?

 

[Onetap]

The radiators are shown connected as a single pipe system; I'm sure you don't intend that.

A standard 2 channel & HWS controller would be able to enable the boiler when there was a demand from either of the 2 heating zones or the HWS. You need to be able to enable it when there's an UFH demand; the UFH has a much higher thermal capacity and longer thermal response and would usually need to run when the rads are off.

Also check the minim um flow rate through the boiler and whether it needs a by-pass. The UFH zone only could be running (and so operating the boiler) with a very small proportion of the flow from the boiler and the rest of the UFH flow water being drawn from the return.

I don't think you'd get reverse circulation through the UFH, since it would be isolated by the zone valve; however, it's good practice to connect the cylinder return last. I'd connect it that way, even if not essential.

 

[Boilerman2]

Acurate "as fitted" drawings are essential if you want sensible feedback on your project your drawing provided has so many errors and would not work correctly why are you fitting one pipe CH circuits why the expense of a programmer and zone valve to run just one Towel Warmer???

Incorrect Return arrangement would cause reverse circulation as has been said Cylinder must be the nearest return to the boiler!!

please revise your drawing so we can advise again

 

[Stamina]

underfloor and rads in same room?why?

 

[mickyg]

the drawing is fine if you just want a price from someone to do what you have drawn. Anyone with half a brain will know how to do the job properly. There's a variety of boilers and controls you could use to achieve it, but I would discuss this with your installer as he can recommend stuff he's familiar with to make the installation go smoothly. You will get product recommendations from people with vested interests

 

[Onetap]

underfloor and rads in same room?why?

I would think that is because;

This diagram represents what i'd like to install to my poorly insulated 1890s 3-bed semi in chilly scotland,

And UFH alone will not supply sufficient W/m^2 whilst keeping below the recommended floor surface temperature.

It does suggest that you'll have two temperature control systems in each room (TRV on rad and UFH sensor/thermostat/TRV). The two systems will be hunting all over the place; you should have one sensor (or TRV or thermostat) and one controller controlling both systems.

A better fix would be to spend more on insulation and make the UFH alone adequate and the radiators unnecessary.

 

[gorty]

I've redrawn to make the pipework closer to reality. I'd added two rads I'm having in the garage, the back half of the garage is a sunroom/guestroom, the other rad in the garage is for occasional use when I'm out there faffing about. The reason for the underfloor is to provide an extra heat source for periods of very cold weather, and also to provide an even temperature gradient and generally make it more comfortable, I'm also planning to use ornate cast iron rads, these have a low output, so I'll need the underfloor once it below x degrees outside. The underfloor will be added last and in stages, one room at a time. The house is difficult to insulate, solid walls and a Mansard roof. I want control of the towel rail so I can heat it in summer without having any rads on, I don't mind the extra cost of a zone valve and programmer, and I might start modifiying the plans to reduce costs later, based on any feedback I can get.

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• gorty
• 1 Feb 2011
• 1

 

[gorty]

A Viessmann Vitodens 200-W with a Sub-mounting kit with mixer and weather compensation will do almost all of this with its built in controls. You will otherwise need a blending valve of some sort for the ufh. Ask their Technical department.

You have shown the two rad circuits as series connections, not even a 1 pipe.

I've looked at the Viessmann Vitodens 200-W

What is the advantage of mixing the UFH water locally at the boiler? I'm assuming it's only a small saving in efficiency as your not heating water to 90-ish-degrees to mix it down again at the UFH manifold.

If I go for this boiler, am I tied to Viessmann boilers forever? or in future could I install another mixer product next to the boiler?

What stops the radiators and UFH in the same room from fighting each other to be in control? I want the radiator to heat the room quickly, but most of the heat used to maintain the temperture of the room to come from the UFH. Example, Livingroom: Zone1 radiators on/off control is by a thermostat in the hall, livingroom rads will have TRVs, livingroom UFH will have thermostat mounted to the wall in livingroom. How do I ensure the UFH does not turn off as a result of heat suppleid by the radiators, leaving the radiators in control and the UFH off?

An underfloor installer friend has recommeded I control the UFH based on floor temperture instead of air temperature. I'm finding that most installers either know about radiator based systems or UFH systems, but not many people have experience of both.

I've queried the technical sales reps for Vaillant, Veissmann and WB, so hopefully I'll get some technical design advice soon.

 

[universal]

In my experience of the viessmann system most people do not understand how it works, but it works very well. I think you wold have trouble moving away from viessmann in the future but that would be due to your satisfaction with their advanced technology. Shame they have developed a poor attitude to their customer support in recent times. If you ring their technical help line and ask to speak to Hugh Pete he will enlighten you. This guy is old school but with it at the same time. His years of experience have been invaluable to me. Don't waste your time with the rest.