Replacing old rads, only 8mm pipe to the old Rads.

[maxibyte]

Hi,
I think that the rads are undersized for my room needs as in the winter the the rooms never really get up to temperature.

The rads are mostly old style single pannel with no fins.

I was thinking of replacing them with double panel with fins.

However, the pipes feeding them are only 8mm. Seems to be 15 or 22 mm pipes leaving the boiler.

Boiler was replaced by previous owner 3-4 years ago. However, the old rads were kept.

I am looking at putting wooden floors down.

Hence I want to determine if the pipe work and the rads need replaced before putting down the flooring.

Thanks for any comments and help.

Gareth.

 

[spm8]

Would be nice and easy to upgrade to 15mm pipe work to rads with the floor up and give a better flow to the new rads

 

[maxibyte]

The new wooden floor will just be sitting on top of the existing wooden floor boards.

Hence it will still require effort to install it.

My Q is really is 8mm suitable for new rads or will I have to upgrade.

Pros and cons of either option if any.

 

[Plumber90]

What are the size of the radiators that are causing the issue?

 

[jeff the gasman]

Before you fit your floor get a plumber in to see if your system can be balanced/ commissioned. Nothing wrong with 8mm pipe on a healthy system but a by- pass fully open will fook up all flow to this type of system as can an incorrectly set cylinder thermostat.
Jeff

 

[Terry lambert]

As above, or weak pump, poor water condition

Also do all the rads get hot but still not heating the rooms or are the rads tepid

 

[loafer]

If you are going to overlay nice t&g flooring then definately consider examining pipe sizing and run(s) issues beforehand. Dont forget if the drain off is presently underneath the floor then doc's will have to be fitted above floor level for every dropped leg on the heating circuit.
Can't understand why existing rads are undersized
How old is the property Has it got double glazing cavity wall insulation adequate loft insulation
Are the rads getting hot all over, top n bottom (Sludge/air)
What gasman said in previous post is very very relevent. Diff by-pass and cylinder stat.

Laminated and or tiled floors are a real pain to a tradesman. Once theyre down theyre down! If there is inadequate crawl space and lack of access to the floor void any form of upgrade/remedial work afterwards is going to be very very difficult if not nigh on impossible!

Don't forget to buy some nice matching pipe collars for the rad tails once your floor is put down.
Good Luck!

 

[maxibyte]

Thanks for the replies guys:

@Plumber90
For example:
Rad in bedroom is single panel, no fin. 3'6" x 1'9".
Room size is roughly 13' 9" x 12' 9". 1 external wall with a bay winow.
Rad is on wall opposite the bay window.

This is just an example of one room.

Most of other rooms have single panel no fins.

I should really measure each existing rad and try to determine what BTU they are giving out and what they should be.

Is there anywhere online that will advise of the BTUs given out for various sizes of old style rads?

@ terrydoh
All rads around house do get hot. However, rooms still feel cold. I think the heat is disapating before it gets a chance to heat up.

@loafer
The boiler is in the bathroom upstairs. Hence I don't think the drain off will still be a problem?

Property is a 1920's semi. Boiler was replaced a few years ago. However rads look old as they do not have any fins.

Correct depth of loft insulation installed last winter. Double glazing throughout. Walls are single skinned (no internal insulation).

I think all the rads are fine heat wise (top and bottom).

 

[maxibyte]

Also, the wooden floor is only downstairs.

However, not sure if it is worth replacing all rads up and downstairs.

Getting a log fire fitted in living room.

Plan is to heat downstairs with wood.

Then mainly use rads for heating upstairs.

1 of rads in living room looks to be big enough.

However, it is behind the couch (2-3 " away).

I take it that this would limit heating of the room.

Would it be worth it to move the rad so that it is under the bay window?

 

[Terry lambert]

Rads are a lot more efficient under windows or coldest part of the room as they work mostly on convection currents rather than radiant heat

Having them covered would affect there performance

 

[D_Hailsham]

You can find output information in the Stelrad Catalogue,page 45. (Other makes will only differ by 1-2%.) If your rads are a different size, just choose the nearest then adjust the output proportionally to the dimensions.

You said the boiler had been replaced before you moved in. It might be worth checking that the boiler is correctly sized. Use the Whole House Boiler Size Calculator to find what size boiler you really need.

If you have a combi boiler, the output will be much more. However some boilers can have the CH output reduced so it matches the CH requirement.

 

[Agile]

To see if each rad is getting enough flow you would need to measure the flow and return at the pipes.

Even a hand assessment is a help.

Just hold pipe 50 C, hold for 3 secs then 60 C and only hold for 1 sec is 70 C.

With a new boiler it should be 15-20 C differential at each rad!

Tony

 

[maxibyte]

Thanks D_Hailsham.

With the Stelrad PDF, do you know if I should compare my old rads to 50, 40 or 30 t?

 

[mogget]

The delta T quoted in the catalogue is the difference in temperature between the rad and the room, so say your flow temperature is 75degC then use delta T 50, if using another flow temperature use the appropriate delta T but with a standard boiler system use the 50degC delta T. (Edit, unless you want to use a lower flow temperature).