"Modern" radiator design and controls?

[mjsx]

I'm renovating a Victorian terrace. What is the best way to heat the property (via radiators)?

 

I was thinking:

 

- a manifold

- MLCP pipe running direct to each radiator (individual control, reduce chance of leaks)

- thermostats in each room, controlling electrothermic actuators on the manifold

 

So basically the approach described here: https://emmeti.co.uk/products/heating-manifolds/

 

However:

 

- Emmeti seem to be the only manufacturer of manifolds for radiators, so this is potentially a niche approach? Does anyone else sell something similar?

- I don't know if their kit is any good … and also they don't seem to have released many new products in the last few years. Is the company going to disappear?

 

Questions:

 

- Is one manifold (for 12 rads) sufficient, or should there be one for each floor?

- Can you connect multiple rads to a single manifold port? Is this a good idea?

- How does the boiler know when to come on? Is that controlled by a separate thermostat?

[SteamyTea]

Have you done a room by room heat loss calculation to correctly size the radiators to the expected load.

Get that bit right and you do not have to bother with individual room controls.

[JohnMo]

Loads of zones, means your boiler just can't modulate low enough, lots of on/off cycling uses more energy.

 

On off controls are no use, you would be better with a modulating Trvs, or better still no Trvs and just balance the radiators to match room heat requirements.

 

Try to have just a couple of zones, bedrooms and living space.

 

Manifolds, plenty out there, look for plumbing manifolds. Most the plastic pipe manufacturers make them. Or use an UFH manifold and use the flow meters to balance the flow to the radiators.

[Nickfromwales]

TRV’s are cheap and reliable, and reasonably accurate tbh. Been fitting central heating for nearly 30 years so I’ve installed ‘a few’ of them. 
Manifolds are fine, done plenty of them to rads via actuators / wall-mounted room stat per room, but a bit OTT tbh.

I mostly employ this type of system strategically in major developments / builds / refurbishments so you’re not continuously draining down and re-filling as the project progresses. 
Why are you so averse to standard series plumbing? Copper pipe with soldered joints are good for a minimum of 30 years, and I have hundreds of these types of installs under my belt without issue. Yes the odd leak here and there at the point of commission, but no different to any other system. Guys installed with Pressfit for me the other day, 2 failed joints, and a PITA to cut back and re-make the duff ones as the pipe gets compromised with the compression of the joint. Soldered joints; just re-flux and sweat it again ( if it has leaked from the first fill up ).

 

Zero manifolds, additional pumps and controls / manifolds wiring centres etc if you install ‘traditionally’. Remember that you can go for smart TRV’s and “whole of house” smart heating controls for not much money. 

[mjsx]

Thanks for the replies! You’re all … skeptical. Makes me wonder whether I should do this.

 

I don’t think I’ve ever lived in a house with properly “balanced” radiators—is it possible?
 

(Among other things, solar gain seems like quite a big factor, and I don’t see how balancing can compensate for that—need individual control. Or should weather compensation deal with that bit?) 

 

And once you go down the route of controlling each radiator, manifolds seem to have a lot of advantages over TRVs (control in a few places, less clutter around rads, no need to change TRV batteries, can use separate temp sensors, etc.). 
 

Using a small (3-4 port) manifold on each floor doesn’t seem that different from more traditional plumbing—is that a good intermediate option?

[Radian]

1 hour ago, mjsx said:

(Among other things, solar gain seems like quite a big factor, and I don’t see how balancing can compensate for that—need individual control. Or should weather compensation deal with that bit?) 

I'm in agreeance with this. As well as solar, kitchens can get hot through cooking. No amount of balancing or weather comp helps with this. I do however think there are plenty of rooms that could do without TRV's - especially on the ground floor. TRV's everywhere coming up to setpoint can play havoc with boiler return temperature and cycling.

[SteamyTea]

On 31/01/2023 at 00:24, mjsx said:

Victorian terrace

 

2 hours ago, mjsx said:

solar gain seems like quite a big factor

I have had Victorian Terraces, solar gain was never a problem.

Even in my current terrace, solar gain, with the occasionally most powerful sunlight in the country, is not a problem.

Are you sure you are not mixing up solar gain with increased external air temperature?

Edited February 4, 2023 by SteamyTea

[SimonD]

I come from the opposite end of the spectrum of experience compared to @Nickfromwales in that I've only recently achieved my badge of heating engineer with about 1 years worth of experience and in that time I've already learned enough to go with what he's said. Keep it simple. I've designed and installed my own heating system using manifolds, but I've gone low tech. I made my own manifolds that simply have full bore lever valves, trvs on each radiator and uses basic push-fit fittings with polybutylene barrier pipe (great stuff if you make a mistake). However, my house was a bare shell so easy to do all the pipework like a spiders web emanating from a fairly central position. In your situation I'd be inclined to go the traditional route.

 

I'm also of the view that trvs are not a problem. Fairly recent research suggests with heat pumps that trvs are fine (e.g. don't dramatically affect the cop) as long as the cycling time of the boiler isn't too short and if it is, you can re-position the main controlling thermostat, add volume to the heating system or even increase the system delta T to reduce the effects of this.

[Radian]

30 minutes ago, SteamyTea said:

Even in my current terrace, solar gain, with the occasionally most powerful sunlight in the country, is not a problem.

Are you sure you are not mixing up solar gain with increased external air temperature?

 

Can be a big problem. It certainly is for some of my windows. Add up all the square meters of glass on a particular elevation, multiply by 0.2 and feed that into PVGIS as Installed peak PV power [kWp] along with 90^o slope and the azimuth of the wall they're installed in (-90° is East, 0° is South and 90° is West) and you can see the monthly and yearly contribution to your heating.

[SteamyTea]

4 hours ago, Radian said:

Add up all the square meters of glass on a particular elevation, multiply by 0.2 and feed that into PVGIS as Installed peak PV power [kWp] along with 90^o slope and the azimuth of the wall they're installed in (-90° is East, 0° is South and 90° is West) and you can see the monthly and yearly contribution to your heating.

Then multiply by the transmission and reflection factors.

 

I think part of the problem is that sitting in a room with a sunbeam on you makes you, as opposed to the room, feel warm.

 

I am tempted to one of my bigger analyses on the effects of solar gain on my house.  Just need to collect more historical weather data.

 

 

[Radian]

58 minutes ago, SteamyTea said:

Then multiply by the transmission and reflection factors.

 

Already in the default PVGIS System loss (14%) Actually, I think Feynman showed the reflection loss is more like 4% with his QED. It seemed like a reasonable conservative guestimate though.

[SteamyTea]

2 minutes ago, Radian said:

Already in the default PVGIS System loss

Different type of glass chemistry, and thickness.

 

I did make up a spreadsheet many years ago that calculated it, think it is on an old backup disk somewhere.

So may have to rewrite one, especially as I am trying to move from Excel to LibreOffice Calc.

Even Excel 200 is so much better tan the last but one version of Calc, just waiting for the Portable Apps people to get the updates sorted for my version.

[Radian]

2 minutes ago, SteamyTea said:

Different type of glass chemistry, and thickness.

 

I only meant it as a hand wavy way of accounting for the optical transmission losses. I don't know about yours but my windows are always filthy anyway.😄

[SteamyTea]

4 minutes ago, Radian said:

I don't know about yours but my windows are always filthy anyway

Yep, that special coating of sea salt, seagull shit and wood burner soot.

 

Back to the original point about a Victorian terrace over heating, they are generally thin and deep, so the ratio of window area to volume is all wrong.

End terrace with a south facing side may give problems, the ratio is all right for over heating.

 

When we had the server heat warning down here year before last, my house did get hot, and I did take tin foil to my window frames.  This dropped the room temperature about 10°C, it then was just a little higher than the external air temperature.

But that was a extreme case, and we had nothing like the temperatures recorded up country.

If I have left the down stairs windows open all the time, it would have probably have been better, but the heroine dealer across the road would probably have stolen my furniture to put on his fire (thinking about it, not seen him for a few weeks).