Balancing Rads

[diynoob]

I'm trying to balance my central heating, but all the guides assume the each radiator has a TRV at one end and a LSV at the other. In my case all rads have 2 LSVs.

Should I leave the flow side fully open and adjust the return side in order to balance? Is it corrct to assume the the hotter side is the flow side?

 

[rego]

yes

 

[bathjobby]

Well, if the hotter side is not the flow, then you've cracked the worlds energy needs - cool in, hotter out just think about it.

 

[diynoob]

I have balanced the central heating now and the rads that were previously cold or slow to heat up are now hot.

Unfortunately, the living room is still freezing. Some info on the room:

- It's the biggest room in the house with a high ceiling (17'x17'x17')
- Rads were luke warm (now balanced so ok)
- There is a chimney (have blocked this up for now, leaving some ventilation)
- The room is off a stairwell
- Its above a double garage
- The large window is not double glazed
- Patio doors are not double glazed

Not sure what to do next. Since the whole house is single glazed and this is the only problem room my feeling is that the garage is the problem.

Thanks.

 

[D_Hailsham]

- It's the biggest room in the house with a high ceiling (17'x17'x17')

17 ft high??!!

my feeling is that the garage is the problem

Possibly.

Check if there is any insulation under the living room floor. You can check from the garage, though it may mean removing some plasterboard hiding the joists.

If no insulation, get some installed (to depth of the joist); and if no plasterboard hiding the joists, get that done as well.

What insulation do you have in the rest of the house - loft and cavity wall? You can get very good deals at the moment - check out Energy Savings Trust Grants and Offers

 

[TicklyT]

With manual valves it generally makes no difference whether the LSV is on the flow or return.

TRVs are usually fitted on the flow side, so if they are fitted, the only place left for the LSV is the return.

Usually the only difference between lockshield valves and wheelhead valves is just the plastic cap. Wheelhead caps turn the valve spindle, and LSVs just have a blanking cap. Fitting wheelhead caps to one end of each rad. would at least give you some control over the output of each rad.

Balancing using the LSVs only sets the maximum heat INPUT to each rad. After that, the wheelhead valve (or TRV, if fitted) is usually used to control the radiator OUTPUT.

Try some of the on-line rad. size calculators, and see how your rad. sizes compare with their recommendations. Don't be too surprised if different calculators give vastly different answers. Some only deal with the heat loss. Naturally, the heat input needs to be greater than the losses to actually raise the temperature.

Is the thermostat in the living room, or is it in a part of the house that warms up quickly, and shutting down the heating before the living room gets a chance to warm up?

Good insulation should cut the heating requirements substantially.

 

[ajrobb]

Blimey, 17'x17'x17' is almost as big as my first 2-bed house (27'x12'x15')!

What radiators do you have in there? (number, lengths, heights and panel types)

How many outside walls?

Age of building and type of construction?

 

[D_Hailsham]

Naturally, the heat input needs to be greater than the losses to actually raise the temperature.

But that does not mean you need to oversize the radiator.

Heat loss is proportional to the difference in temperature between the house and outside. So if both are at the same temperature, there is no heat loss.

If you then turn on a heat emitter in the house the temperature will rise until the heat lost due to the increased difference in temperature between inside and outside balances the heat given out by the heat emitter.

Radiator calculators often allow about 10% extra to give faster warm up. This is mainly for situations were the house is only heated in the morning and evening.

 

[ajrobb]

I've played with

http://www.energysavingtrust.org.uk...ng-sizing-wizard/Domestic-Heating-Sizing-Tool

Assuming roof with 50mm insulation, non-insulated cavity walls, metal windows, no underfloor insulation and 3 external walls, blah, blah it suggests 7.6 kW of heating.

Assuming roof with 200mm loft insulation, filled cavity walls, wooden windows and insulated floor => 5 kW

With modern double glazing and wall insulation to current regs => 3.1 kW

 

[ianniann]

Even regular sized single glazed windows are likely to be the biggest single heat loss from a room. Over-sized windows plus patio doors are the first place to look for your cold room even if the walls are insulated. The open stairwell (no doors?) won't help either. The ceiling is the roof, I assume? Top floor rooms also have higher heat loss, very high if the roof space isn't well insulated. Being over the garage may or may not be a problem. I'll suggest not a massive problem unless you have serious drafts coming up through the floor. Might be the cheapest one to insulate though ...

You still haven't said what radiators are in that room. If the room is cold, it is a pretty simple thing to tell you that the radiators are not meeting the heat loss from the room, or at least not exceeding it enough to warm up the room. In a room that size it becomes difficult to provide enough conventional radiators. Perhaps you can slap a fan-assisted one in? The output can be massively higher than even a finned double passive radiator.

 

[diynoob]

Thanks all for the replies.

17 ft high??!!

No my mistake, it's a sloped ceiling. 7' at one end and 13' at the other.

Check if there is any insulation under the living room floor. You can check from the garage, though it may mean removing some plasterboard hiding the joists.

I haven't been able to check. The garage ceiling is boarded and plastered.

Is the thermostat in the living room, or is it in a part of the house that warms up quickly, and shutting down the heating before the living room gets a chance to warm up?

The thermostat is in the hallway, which is the part that heats up quicker as you say. The rads in the living room aren't shutting down too soon. They are too hot to touch but still the room is cold.

What radiators do you have in there? (number, lengths, heights and panel types)

How many outside walls?

Age of building and type of construction?

2 rads, they are both the double finned ones and are 60cm high. One is 190cm long and the other is 95cm long.

The room has 3 external walls. One with a large window, one with patio doors and one with a chimney!

The house was built in 1982 and is brick and part weatherboarded.

Even regular sized single glazed windows are likely to be the biggest single heat loss from a room. Over-sized windows plus patio doors are the first place to look for your cold room even if the walls are insulated. The open stairwell (no doors?) won't help either. The ceiling is the roof, I assume? Top floor rooms also have higher heat loss, very high if the roof space isn't well insulated. Being over the garage may or may not be a problem. I'll suggest not a massive problem unless you have serious drafts coming up through the floor. Might be the cheapest one to insulate though ...

The window is 230cm x 130cm. Patio is 230cm x 190cm. Rad sizes as above. Yes the ceiling is the roof. The loft has insulation but the loft does not extend over the living room unfortunately. Entering the room bare foot, the floor temperature is very noticeably colder than the other rooms, although holding a candle to the windows does flicker which tends to implicate the windows.

I'm reluctant to rip up the living room floor or the garage ceiling if it can be avoided. Would it help if I covered the garage ceiling in PIR insulation board? I could do that myself. Otherwise I could get someone in to squirt something into the cavity if its not been insulated.

If I'll get more benefit from improving the windows I could get them replaced. The house will need double glazing eventually, they are wooden frames. Having moved recently I can't get the whole house done at the moment but could probably afford to get the living room window and patio doors done.

Would be good to get some more clarity on the main cause of the cold though.

 

[ajrobb]

[quote="diynoob";p="1919987 2 rads, they are both the double finned ones. One is 190cm long and the other is 95cm long.[/quote]
How high?

In 1982 I suspect you might have 50mm of mineral wool insulation in your flat roof. Warm-roof insulation would put up to 150mm Celotex on top of roof. Behind the weather boarding you might have 25mm of mineral wool.

You're probably closer to 7.6kW than 5kW heating requirement.

Regarding insulating garage ceiling, I'd have a word with the Local Authority Building Control as it is a fire barrier.

 

[diynoob]

Taking the average height of the sloped ceiling, the living room is 5.2mx5.2mx3.0m.

Rads are 60cm high. My guess is they output about 4kW and the room requires 5kW-7kW depending on the roof and wall insulation.

I got the multimeter out that I balanced the rads with and wandered around the house. The thermostat is set to 27C. I got a consistent 27C reading upstairs, sometimes 26C downstairs.

The living room is 24C at head height (feels colder than that though) but 19C at floor level.

 

[ianniann]

The thermostat is set to 27C.

Were you born in a tropical rainforest?

 

[diynoob]

Hehe, its not normally that high. I turned it up before the test. Although I'll have to keep it at 20+ or the living room will be too cold.