Feed and expansion loft radiator

Z

ZeeshanTC

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Hi All,

I'm not an expert, but am willing to learn and have a go and save money. I've previously installed several radiators on a combi.

I've just got a new house a started doing an extension, build it with my brother , our first attempt, so pretty chuffed.

The house, after extension will be a 6 bed house, with 3 bathroom(2 en suite). The boiler is a baxi solo 30 he. I have absolutely no idea if this is good. I've been googling around and it appears we have a feed and expansion system. Basically there is a couple of tanks in the loft, one big one (cold) and a smaller one (f and e , I believe). I also have another tank in one of the bedrooms which I believe stores hot water.

A week ago, I attached 2 new radiators to the existing system, one in the loft and the other 2nd floor(bedrooms). I didn't get any heat in the radiators so I bled all radiators. One of the radiators, on the 2nd floor, started letting cold water from the bleeding nut. The other radiator in the loft had no water at all in the radiator. This got me thinking and I thought it might have something to do with the f and e( gravity fed) system. So we took the loft radiator out of the equation. We then concentrated on the rad on the 2nd floor and after some googling, balanced the radiators which got us some heat.

This started to raise some questions.
1. How can we get the loft radiator working , or should it have just worked and it's best we try again. The level of the f and e and radiator is about the same.
2. Is our current boiler good.
3. Should we look at getting a different system.
A. Combi boiler
B. Sealed system kit
C. Leave existing and connect extended side to new combi.

Thanks for all your comments in advance. Go easy on me, my first post.
 
ZeeshanTC said:
The level of the f and e and radiator is about the same.
Click to expand...

That's probably why there's little or no water in the radiator. The base of the F & E tank must be higher than the top of the highest rad.

A sealed system would remove this problem, (and find some leaks for you).
 
Raising the F&E tank above the highest radiator will cause that radiator to fill. The vent pipe must rise continuously.

If this is not practical, then an expansion vessel of the correct capacity can be added.
You will need to find out where the feed and vent pipes join the rest of the pipework, and disconnect them. Your boiler manual states where and how to install an expansion vessel, pressure relief valve and charging point with respect to the boiler and pump positions.
This will pressurise BOTH the radiator pipework, and the flow and return to the hot water cylinder, so you MUST ONLY do this if the cylinder is indirectly heated. Also beware that the increased pressure may open leaks where there were none before - typically at older radiator valves and, if you are unlucky, existing compression fittings.
 
Last edited:
Thanks echoes.

Since my first post I've added another radiator to the baxi sole 30 he. The new radiator did not heat up, it had water in , but cold. I turned all radiators off except the newly added and it got some heat, I then did a quarter turn, balancing and bleeding, on other other radiators. This led to the same, cold radiator again. I now have 9 rads downstairs and I need to add a further 2. I have 8 rads upstairs and need to add another 1. I also have a loft radiator which I mentioned in my earlier post, which didn't get any water to the radiator, so I disconnected it.

I'm planning on adding the extra radiators but not sure the best way how to tackle this problem and if my baxi solo 30he will support these rads.

@echoes I'm not sure if the cylinder is indirectly heated.

I've read a few places that a combi is not really sorted for the amount of rads and bathrooms I have.

I'm not sure what the best solution is for my position.
Expansion vessel? - if so can anyone recommend any and what capacity I need.
Combi? - shall I stay away from this.
Stick with what I have - keep what I have. Any recommendations on sorting the cold rads.
Any other?

Thanks
 
A Combi will be fine on heat output, your problem is the resistance on the pipes to your new rad is too high.
You either need a bigger pump or bigger pipes from the existing one to that rad.
If the resistance of all your existing rads is similar and that one is double, the water will be very slow to reach it.
 
ZeeshanTC said:
Thanks John, all pipes including new are 15mm.
Click to expand...
resistance is proportional to the overall length as well as being affected by the pipe diameter
also I forgot to mention that if the new rad shares any pipes with the existing system then the pressure drop on those pipes will increase a fair bit
 
Ahh I T'd of an existing radiator which T'd off another. So I'm guessing it could be an issue with resistance/pressure. What would be the best way forward.

I just had a look at the airing cupboard and I think I've found the pump it's bosch part number 59526639

Thanks
 
ZeeshanTC said:
Ahh I T'd of an existing radiator which T'd off another. So I'm guessing it could be an issue with resistance/pressure. What would be the best way forward.
Click to expand...
That explains it, basically it'll be impossible to balance and get any meaningful heat output. You might be able to disconnect from the rad you teed off and connect it to where the main branches of the system are, where it's still 22mm pipe, and this means the new rad has all it's own pipework. Failing that you could replace all the pipework that rad shares with others with 22mm and throttle those ones down plenty.
In an ideal system each radiator t have a dedicated pipe run of exactly the same length and no pipes would be shared, but unless you have an ufh manifold that would be hard to achieve.
 
Thanks John,

Looks like it's 15mm almost all the way, there is an area which looks tricky to get to, even if I got to to the area it looks tricky to send pipework from there.

T from original rads with 22, looks like an option for 1 of the 3 rads, might be tricky but I could try. Problem I have is most of the floorboards are on now, plus the joists are in a different direction making it impossible to get pipes in. By the way, I have used pushfit, to get around this.

Do I have any other options. John you mentioned something about a bigger pump, is that an option. Also is expansion vessel an option.

Thanks again
 
Expansion vessel is not relevant, bigger pump (ie more head) might help but you might end up with other issues as the rest of the radiators will have to be turned right down.
I can't help much more as this is a situation where practical experience is needed, I can only tell you the theory.
Perhaps some of the more experienced members will help out further. Good luck.
 
Unfortunately Z, you need someone experienced with CH systems to look at your current setup and show/tell you where it needs work to allow expansion. It's a bit of a common misconception that radiators can just be added without looking and understanding the current setup and how/what can be expanded without issues.

Don't get me wrong I'm not saying that you can't expand/add to your system as a DIY job but you do need to have someone who is experienced to look at your system and give you a design and show you the correct approach. It's nigh impossible to do that without being onsite. Throwing pumps and pipework at it hoping it'll work is not the way forward I'm afraid.
 
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