Does a radiator like this make sense?

FreeBear

pieroabcd said:

Pump speed on the boiler? There's no setting for that in the menu. Maybe the gas engineer can do it?

On mine, a Viessmann 050. Enter the service menu by pressing magic buttons, and then selecting the correct menu number - https://www.manualslib.com/manual/3456670/Viessmann-Vitodens-050-W-B0ha.html?page=42

If your boiler is fairly modern, it may well have a speed option - Tell us the make, model, and year, and I'm sure we can find the manual. With older boilers, it may just be a switch on the back of the pump with 3 settings. If it is behind the main (sealed) cover, then a Gas Safe engineer should change the setting for you. One or two would advocate removing the cover yourself.

pieroabcd

Vaillant ecotec plus 837.
The gas engineer is due at the end of the year, so... I'll ask him

FreeBear

pieroabcd said:

Vaillant ecotec plus 837.
The gas engineer is due at the end of the year, so... I'll ask him

Hrmmmm... Looks like there might be a couple of different pumps fitted inside. Cheap Wilo single speed, more advanced Crew which has 3 speed settings, or a Grudfos with lots of options. It is a cover off job to change the pump speed (if it is even possible)...

pieroabcd

Question: what's the best positioning for TRV, on the flow or on the return? 

FreeBear

pieroabcd said:

Question: what's the best positioning for TRV, on the flow or on the return? 

Usually on the flow. You can get some that will work on either end, but I'd still put them on the flow.

pieroabcd

Today for the first time I touched the bottom of the column radiator in the loft ( 40cm high) and I noticed that it's cold. Sludge?
Any solution that doesn't cost a fortune?
I've read of chemicals to inject in the pipes, but I wouldn't want to cause a damage. 

ThisIsWeird

pieroabcd said:

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? 

I think step back and make a cuppa time! Let's not overcomplicate things.

For instance, I would not go anywhere near the pump speed, as it isn't a separate pump with a 3-position switch that invites such fiddling. There is nothing to suggest, at the mo', that the pump speed is an issue here, but if you did manage to mess with it, I'd bet it would become an issue...

We also need to get our terminologies correct so there is no misunderstanding, and we can all follow the steps taking place. For instance, what do you mean by, "...even though the flow valve is barely open" above?

When you are balancing radiators, all the 'flow' or 'control' valves - TRVs usually - should be fully open on every radiator. The only valves you will be adjusting are the lockshields.

So, starting with a cold system, and CH off;

1) open every control/TRV/flow valve fully, 

2) remove the cover caps from every lockshield ready for tweaking. I think a very useful extra step here would be to determine how far open each one is to begin with. So, close each one in turn by tightening them down fully clockwise until they stop, and note how many full and part turns this took. Write this down. Then reopen them the same amount. Flag up any rad that was open more than, say, two full turns - do you recall if these were the hottest rads before? If so, reopen the l/s on these to no more than 2 turns. Note that down too.

3) Turn on the CH, and run around in circles like a blue-bottomed fly. Note down, as best you can, which ones are heating up fastest, and which are remaining cold. Most, I guess, will be middleish, and that's fine. Write it down.

4) CH off, and it needs to cool down a fair bit. Cuppa time.

5) Then begin with the 'fastest' rad, clip on your thermies, turn the CH back on, and turn the lockshield down to get the required delta-whatsit across that radiator. All radiator 'control' valves need to remain fully open at all times from now on, until the balancing has been completed. (Well, you can shut them off when you've finished balancing for the day, but turn them ALL open again before resuming balancing.)

6) Once you've delta-T'd the fastest rad, go to the next fastest as you recall it. Or, if they were similarish, go to the ones nearest the boiler and work outwards.

Do not turn any radiator off. If you find the next rad's delta is too low (both pipes too hot = too much flow), then you need to tweak down the l/s and give it time to respond and cool down. Another cuppa. Then tweak again to get the delta. I bet you'll soon figure out which rads are way out, and be more blunt with the initial l/s tweaks, then fine-tune them.

This is a slow game. Be patient. Stop when you need to; just note which rads you've done. Then you can shut off any rad (using their control valves, obvs...) you don't need for that evening, until you are ready to continue the process again. When you resume, ALL CONTROL valves on ALL rads need to be FULLY opened again.

This looks good: https://www.onlyradiators.co.uk/blog/how-to-guides/balancing-radiators-guide

pieroabcd

I like this "back to basics" because a lot of misunderstandings come to light.
In several descriptions that I read there are a lot of assumptions, like that the TRV is on the flow valve carrying hot water from the boiler. 
In my house, where they are present it's the opposite on all but one radiator (the one that I installed correctly... By mistake).
So when last year I balanced my system I tried to do this gradual opening, but on the lockshield valves that in my case are on the flow valves, not on the returns. I had noticed that if I didn't close by a good measure the returns I had no effect.

So good, I'll have to do everything from scratch, but at least this time understanding the reasoning. 
I should probably move all TRVs on the flow side, but for that I definitely need help from my trusted friend. 

ThisIsWeird

pieroabcd said:

I like this "back to basics" because a lot of misunderstandings come to light.
In several descriptions that I read there are a lot of assumptions, like that the TRV is on the flow valve carrying hot water from the boiler. 
In my house, where they are present it's the opposite on all but one radiator (the one that I installed correctly... By mistake).
So when last year I balanced my system I tried to do this gradual opening, but on the lockshield valves that in my case are on the flow valves, not on the returns. I had noticed that if I didn't close by a good measure the returns I had no effect.
So good, I'll have to do everything from scratch, but at least this time understanding the reasoning. 
I should probably move all TRVs on the flow side, but for that I definitely need help from my trusted friend. 

If your TRVs are relatively modern, they should be bi-directional. If you look closely at the sides of the chrome valve bodies, see if there are any direction arrows embossed on them; a 'bi' will have a two-headed arrow. That's good.

If any have a single arrow which is pointing the wrong way, that could be an issue - you may even hear the TRV rattling as it shuts off against the flow. Chances are, tho', that they'll be fine.

A CH flow is surprisingly powerful. Rads closest to the boiler get a strong flow, and you'll likely find that these lockshields will need tweaking right down, often only a fraction of one turn open. So don't be surprised if you need to nearly close them off.

As soon as you do the 'fly' test (ie, run around checking them for heat-up speed), report back, outlining where these rads are. You could even do a MickeyMouse 3D 'box' sketch of your house, showing each room and rad, and where the boiler is located. Label each rad with its 'speed', and later with its initial l/s setting. That would be useful. And fun to see your drawing skills.

FreeBear

ThisIsWeird said: If your TRVs are relatively modern, they should be bi-directional. If you look closely at the sides of the chrome valve bodies, see if there are any direction arrows embossed on them; a 'bi' will have a two-headed arrow. That's good.

If any have a single arrow which is pointing the wrong way, that could be an issue - you may even hear the TRV rattling as it shuts off against the flow. Chances are, tho', that they'll be fine.

.... And it is possible to use unidirectional TRVs on the return as long as the arrow points in the right direction (forgot about that in my earlier comment). This is why you sometimes see TRVs mounted with the head horizontal.