Does a radiator like this make sense?

pieroabcd

FreeBear said:

pieroabcd said: Would it be better to replace this radiator with a full length, half height one?
If heat tends to rise it won't do me the favour to go down to keep me warm.

The first step is to measure the size of the room and window/door area. Then punch the numbers in to an online heat loss calculator. I use this one -> https://www.stelrad.com/basic-heat-loss-calculator - A Delta-T of 50°C is OK for a gas/oil boiler with a 70°C flow temperature.

Once you know what size radiator you actually need, you can make an informed choice. If you can't get the room up to a reasonable temperature, you need a bigger radiator (or cut the heat loss).

Heat required 4138W / 14129BTU.
If the radiator is this one https://www.justradiators.co.uk/sale-lux-heat-vertical-coloured-column-radiators
that has 1381 W, even adding the other one (presumably from 1/2 to 2/3 the size and BTU) I'm well under specs.

Uhm...

ThisIsWeird

pieroabcd said:

ThisIsWeird said:

pieroabcd said:

Yes, i mean in terms of heat output. 
Given two radiators with the same thermal capacity,  in terms of heat distribution is it better one that is longer rather than taller?
The balancing in this system was a bit of a nightmare. I had to do 4 or 5 tests to get a good result (as I wrote in another thread) because when I moved in I couldn't get any heat at all at the second floor.
Now it's working, but I had to sacrifice a bit this corner of the lounge ( not too much). 
The boiler seems to have 14Kw of power, so it should be more than enough.
When the flow valves are fully open and they receive water all rads get scalding hot, so it's definitely a matter of balancing. The tall ones get a bit less hot at the top, probably unavoidable? It doesn't happen to the regular rads, though. 
I bleed the radiators very frequently (twice a month in winter). Only the first two times I've seen some air. The water has always been spring clean. 
The pressure... This boiler simply refuses to work with less than 1.4 bar, complaining that there's too little water. 
Still to keep the pressure low, I keep the water temperature at 60 degrees, that serves me well in terms of comfort (or I begin to sweat). 
I'll open a bit more the flow valve here until it gets hot enough and I'll check what happens at the second floor. These are the only two variables for the moment. 

As you say, your boiler should be plenty powerful enough.
Most likely, I guess, is you still have some balancing issues.
When you tried to balance it all, did you use a couple of thermometers?
Anyhoo, to try and answer some of your Q's as best I can; although rads with convection fins are more likely to be better at heating a whole room than plain or column types, I doubt there will be much actual difference, if their respective outputs are the same.
And ditto with tall and standard - I cannot see it making more than a marginal difference either way.
Column rads should be hot all over - the I ternal water flow is designed to ensure that. But, like any rad, if they ain't getting enough flow, then it's the top that will suffer, and it makes 'sense' to me that tall rads would be especially vulnerable to a lack of flow.
Also, column rads must be connected the right way around - are you certain yours is?
I take it that subsequent bleeding does not produce any more air? Once settled, a sealed system should produce next to zero 'air'.
 How many storeys do you have? You may well need a higher system pressure if, say, 3, so that might explain the reluctance to operate below 1.4. 
In any system, 1.4 is ok anyway, not at all too high.
Do you have an analogue gauge? Either way, do you notice that the pressure drops the moment you turn on the CH? 
Does the pressure vary much, up or down, in use?
How many rads do you have?
Clean water is obviously a good sign? Do you also have a mag filter fitted? Inhibitor levels good?

Some difficult questions. 
I don't know if the columns rads are connected the right way round. I found them installed when I bought the house. How can I check?
Successive bleeding didn't release any air. 
What's the CH? 
The pressure ranges from 1.4 to 2.5-2.7 when the temperature climbs from 16 to 19 degrees, as is typical in my home in winter. After it's been off for 30 minutes or more it goes back down to 1.6-1.7.
I have 11 rads, including 3 small (but really hot) ones in the bathrooms.
As far as I know I don't have a mag filter fitted, or at least it's not mentioned anywhere. 
I don't have an analogue gauge, either. 
For whom asked, the ceilings are 2.4 high, except in the loft where they are 2m high.
3 storey house. 

CH is just 'central heating' - when you turn on your rads.
That's quite a pressure swing when hot, more than I'd be happy with. Has your expansion vessel been checked recently?
Being 3 storey, it does make more sense that you need a higher-than-usual starting pressure.
How to check if the column rad is connected the right way? No idea! Mine had labels on it... I'd imagine they are all standard that way, so find installation instructions on Google. Then note which one of your valves become hot first - that's the 'flow'.
I suspect your rad system is not balanced. When balanced, all the rads, regardless of size or location, should heat up at a similarish rate (if they are turned on, of course).

pieroabcd

ThisIsWeird said:

pieroabcd said:

Some difficult questions. 
I don't know if the columns rads are connected the right way round. I found them installed when I bought the house. How can I check?
Successive bleeding didn't release any air. 
What's the CH? 
The pressure ranges from 1.4 to 2.5-2.7 when the temperature climbs from 16 to 19 degrees, as is typical in my home in winter. After it's been off for 30 minutes or more it goes back down to 1.6-1.7.
I have 11 rads, including 3 small (but really hot) ones in the bathrooms.

As far as I know I don't have a mag filter fitted, or at least it's not mentioned anywhere. 
I don't have an analogue gauge, either. 

For whom asked, the ceilings are 2.4 high, except in the loft where they are 2m high.
3 storey house. 

CH is just 'central heating' - when you turn on your rads.
That's quite a pressure swing when hot, more than I'd be happy with. Has your expansion vessel been checked recently?

> Either way, do you notice that the pressure drops the moment you turn on the CH? 
When I turn on the central heating the pressure rises instantly by 0.1, 0.2 and slowly higher and higher.

In January the gas engineer changed the seal, did the servicing and released the gas safe certificate.
Next January I'll ask him to check the expansion vessel too.
BY how much should the pressure rise in my condition?

ThisIsWeird

pieroabcd said:

ThisIsWeird said:

pieroabcd said:

Some difficult questions. 
I don't know if the columns rads are connected the right way round. I found them installed when I bought the house. How can I check?
Successive bleeding didn't release any air. 
What's the CH? 
The pressure ranges from 1.4 to 2.5-2.7 when the temperature climbs from 16 to 19 degrees, as is typical in my home in winter. After it's been off for 30 minutes or more it goes back down to 1.6-1.7.
I have 11 rads, including 3 small (but really hot) ones in the bathrooms.

As far as I know I don't have a mag filter fitted, or at least it's not mentioned anywhere. 
I don't have an analogue gauge, either. 

For whom asked, the ceilings are 2.4 high, except in the loft where they are 2m high.
3 storey house. 

CH is just 'central heating' - when you turn on your rads.
That's quite a pressure swing when hot, more than I'd be happy with. Has your expansion vessel been checked recently?

> Either way, do you notice that the pressure drops the moment you turn on the CH? 
When I turn on the central heating the pressure rises instantly by 0.1, 0.2 and slowly higher and higher.

In January the gas engineer changed the seal, did the servicing and released the gas safe certificate.
Next January I'll ask him to check the expansion vessel too.
BY how much should the pressure rise in my condition?

Some systems, especially larger ones, are prone to greater increases. Ideally you wouldn't want it going much over 2 bar, but the 'safety' trigger is 3 bar, so you should be ok.
Yes, I'd let the GS know of the large swings next time, telling him it hits 2.7 - see what he says.

FreeBear

pieroabcd said: Heat required 4138W / 14129BTU.

That is going to be a darned big radiator. Either that or a pair of type 22 at 1200x600 - You must have a pretty big room. I only need one at ~2kW/7000BTU in a 4mx4m south facing lounge - That said, the north facing room, slightly smaller, is still cold with the same size radiator (calculator says it should be plenty).

pieroabcd said: By how much should the pressure rise in my condition?

I get around 0.5 bar pressure increase. Maybe I need to go round bleeding the radiators again..

pieroabcd

FreeBear said:

pieroabcd said: Heat required 4138W / 14129BTU.

That is going to be a darned big radiator. Either that or a pair of type 22 at 1200x600 - You must have a pretty big room. I only need one at ~2kW/7000BTU in a 4mx4m south facing lounge - That said, the north facing room, slightly smaller, is still cold with the same size radiator (calculator says it should be plenty).

pieroabcd said: By how much should the pressure rise in my condition?

I get around 0.5 bar pressure increase. Maybe I need to go round bleeding the radiators again..

It's the usual lounge plus dining room, open plan. 7.5x3.5 m. 
West facing with 16 sqm of double glazed windows. 

FreeBear

pieroabcd said:

FreeBear said:

pieroabcd said: Heat required 4138W / 14129BTU.

That is going to be a darned big radiator. Either that or a pair of type 22 at 1200x600 - You must have a pretty big room. I only need one at ~2kW/7000BTU in a 4mx4m south facing lounge - That said, the north facing room, slightly smaller, is still cold with the same size radiator (calculator says it should be plenty).

pieroabcd said: By how much should the pressure rise in my condition?

I get around 0.5 bar pressure increase. Maybe I need to go round bleeding the radiators again..

It's the usual lounge plus dining room, open plan. 7.5x3.5 m. 
West facing with 16 sqm of double glazed windows. 

A 2kW radiator at either end should heat the space evenly, and get it up to a reasonable temperature. The other alternative is wet UFH, but that would be hugely disruptive (and very expensive) to install.

pieroabcd

I've put to work those two thermometers. 
On the radiator in the kitchen (t22, 1.5 m long, it gets very hot) the difference is 11 degrees, even though the flow valve is barely open.
On rhe column radiator the difference is 0 degrees. T-in is equal to t-out.
I really don't know how to interpret those numbers, other than something is wrong. 

BTW, there's a direct correlation between the water flow between two radiators on the vertical : if I want enough water at the second floor I have to close significantly the flow valve on the radiator just below it. Not a big problem because the bedroom at the first floor is warm enough, but is it normal? 

FreeBear

Turn your pump speed right down. That should make it easier to adjust the ∆T.

Currently messing with my heating. Pump had been set at max speed, and the best I could achieve was a ∆T 7°C. With a flow temperature of 50°C, it should be around 15°C. Knocked the pump speed down to its lowest setting, and I'm getting a ∆T 12-25°C - 4 hours in, and I've still got 3 more radiators to do.

If one radiator needs shutting down for another to heat up, it sounds like the pipes feeding both are too small. My sis has a near identical problem with a radiator in her granny annex. When it was built, the plumber extended a 15mm drop from a radiator in an adjacent room. That radiator is rated somewhere around 3kW (maybe more), and the new one, 1.5kW. 15mm pipe is only good for ~4kW, and that is reduced if it is a very long run - Plumber in this case was a bit of a berk as the boiler was even closer on the other side of a wall....

Back top pipes. This table from https://www.heatgeek.com/does-my-pipework-need-upgrading-for-a-heat-pump-with-cheat-sheet/ gives us reasonable numbers for the energy carrying capacity of a pipe. If anything, a bit on the high side... Other sources suggest 4kW is the limit for 15mm (it really depends on flow rate & ∆T)

Ignore the bit about hydraulic separation as it has no bearing on capacity.

Once you've looked at the pipe sizes, I suspect the drop (or riser) going from lounge to bedroom could well do with being upgraded to 22mm.

pieroabcd

Pump speed on the boiler? There's no setting for that in the menu. Maybe the gas engineer can do it?
I'll check the pipe diameter. Thanks!!