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Radiators and plumbing


RoseB

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Ok kind knowledgeable people, hopefully you can guide me. 
my question is, when replacing the radiators, should I replace with single or double panel ones?
 

I’ve a 57ft nb, which is 25 years old. Most things on it are that old too. It has an eberspacher D4 diesel heater and calorifier, I’m due to move on in 2 weeks and I’d like to know I can heat water for a shower and put the radiators on. 
I need to service the eber, but last time I tried, it did start up. 
All but one of the radiators are rusty and leaking, so I am going to replace them. They are all 450 high, then 500, 400 and 2 x 800 wide. 
 

Are double panel radiators suitable? better? Hotter?
The two in the lounge have trvs. Shall I replace them all with standard vales?
And please can someone explain ‘balancing’ a system? 

 

Edited by RoseB
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It's not really a question of single or double panel rads, more a case of balancing the output of the heater to the rads + an estimate for the pipework. Better not to include the calorifier as once that's up to temperature it won't be taking any hear from the eberspacher. 

 

So if for example your eberspacher has a 5kW output that's roughly the combined output you want from the rads. Rad output is often quoted in btu but you can easily convert to kW using an online unit converter.

 

Yes I'd get rid of the TRVs if I were you because you don't want the rads shutting down when the room gets warm. The basic idea is to use the full capacity of the heater. If you don't you risk hot water going back to the heater causing it to idle and coke up. The top of the TRVs should just unscrew so you don't need to replace them with standard valves unless you want to. I've just taken all mine off and chucked then away.

Edited by blackrose
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I've been looking at our home system recently, so I could suggest that, for your questions, YouTube is your friend.

 

Double rads just mean you can have half the width, but a bit more depth, (double?), for the same BTUs.

 

I like trvs, as long as you set them and dont keep messing with them: 

 

 

Balancing: lots of videos, with "guesswork" solutions, which can improve things, and "temperature drop across the rad" solutions - just one example, you can search for many more:

 

 

 

 

 

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9 hours ago, RoseB said:

Ok kind knowledgeable people, hopefully you can guide me. 
my question is, when replacing the radiators, should I replace with single or double panel ones?
 

I’ve a 57ft nb, which is 25 years old. Most things on it are that old too. It has an eberspacher D4 diesel heater and calorifier, I’m due to move on in 2 weeks and I’d like to know I can heat water for a shower and put the radiators on. 
I need to service the eber, but last time I tried, it did start up. 
All but one of the radiators are rusty and leaking, so I am going to replace them. They are all 450 high, then 500, 400 and 2 x 800 wide. 
 

Are double panel radiators suitable? better? Hotter?
The two in the lounge have trvs. Shall I replace them all with standard vales?
And please can someone explain ‘balancing’ a system? 

 

answering your questions

a) are double panel radiators suitable? better? Hotter?

The selection between single or double panels would normally be made based upon  required output for the room in question followed by the space available on the wall. For a given output there is no benefit of double panel over single. If fact most radiators come in four styles that is Single panel, Double panel and Double panel with one or two internal fins. On a narrowboat the selection of the Double radiator with fins will result in a wider radiator and could reduce space to pass by, more critical in corridor locations. Irrespective of radiator select they will or operate at the same temperature which is primary set by the boiler controls.

 

b) TRV's The use of TRV's will enable you the regulate the temperature of the rooms in which they are fitted and at different temperatures. Do not fit TRV's to all radiators unless a balancing bypass valve is fitted which is abnormal on boat or small house systems. This enables the pump to operate when the other TRV's have closed down. If you don't fit TRV's then all room will heat up to the same temperatures assuming the balancing has been carried out correctly.

 

c) Balancing: In theory to balance a heating system you want to reduce the flow to each radiator to equate to the design flow rate equal to the heat load required. In practice this is achieved by i) with boiler cold remove all TRV's and set all other valves on both ends of each radiator fully closed and then open one valve on each radiator 1/2 a turn, ii) turn on boiler to operating temperature and pump on, iii)  check the temperature of water arriving at all radiators (by hand if no surface thermometer is available) Ideally they should all be the same. However, in practice the radiator nearest the boiler/pump will be hotter getting cooler as you move along further away from the boiler. iv) Then you need to slightly close the one valve on the hottest radiator to move hot water onto the next radiator and so on along the line of radiators, You may need to move between radiators a few times until you obtain the same temperature to each radiator at which point you have balanced the flow . v) Only after you have obtained this balance you can refit the TRV, since if the TRV's are left in situ and they start to close down you will not be able to balance the system. The U tube video above may help to demonstrate this.

 

Hope this helps

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Re TVRs.  I advise that you take notice of what Blackrose said because you do not have Eberspacher diesel boilers or similar in houses. All makes of such boilers have long been known to carbon up far faster than they need to if the boiler keeps cycling between high and low heat or running for  periods on low heat. They seem to be far more reliable if allowed to run flat out and then turned off if required.

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4 hours ago, Tony Brooks said:

Re TVRs.  I advise that you take notice of what Blackrose said because you do not have Eberspacher diesel boilers or similar in houses. All makes of such boilers have long been known to carbon up far faster than they need to if the boiler keeps cycling between high and low heat or running for  periods on low heat. They seem to be far more reliable if allowed to run flat out and then turned off if required.

So... in reality, no trvs, and a thermostat to control the boiler. That's what I have on my Truma gas warm air heating.

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Thank you all for the links and advice. I’m really grateful.

 

so it seems that if I replace what is currently there like for like, with single panel radiators, they will total 1.7kw. The heater is 4kw I believe. And surely the pipework doesn’t account for 2.3kw. 
Have I a) done bad maths somewhere or 

b) need to put in larger radiators?

 

- triton did the fitout, and I’d be surprised if the original fit-out wasn’t ‘correct’

Edited by RoseB
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On 20/01/2022 at 09:52, Tony Brooks said:

Re TVRs.  I advise that you take notice of what Blackrose said because you do not have Eberspacher diesel boilers or similar in houses. All makes of such boilers have long been known to carbon up far faster than they need to if the boiler keeps cycling between high and low heat or running for  periods on low heat. They seem to be far more reliable if allowed to run flat out and then turned off if required.

 

 

 

 

Thank you all for the links and advice. I’m really grateful.

 

so it seems that if I replace what is currently there like for like, with single panel radiators, they will total 1.7kw. The heater is 4kw I believe. And surely the pipework doesn’t account for 2.3kw. 
Have I a) done bad maths somewhere or 

b) need to put in larger radiators?

 

- triton did the fitout, and I’d be surprised if the original fit-out wasn’t ‘correct’

Edited 17 hours ago by RoseB
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I think you are right. A K11 (one panel with one set of fins) Stelrad  450 by 500 single rad will put out a bit over over  1000 BThU per hour. (Exactly how much depends on the air temperature, the boiler output temperature and how the rad is plumbed). You in effect have 5 (a total of 2500 mm rads 450 high)  of them so more than 5000  BThU/hr.  That is equivalent to  about 1.5 kW 

Allow for the pipes, and something for keeping the calorifier warm and you are up to 2-2.5kW.

 

I would replace your rads with K21 type (two panels one finned) which will take you  up to about 2.9 kW of rads plus pipes and will load the Ebby sufficiently that it does not short cycle, nor will it be flat out like a lizard drinking.

 

I assume your current rads live below the tunnels.  If so you will not notice the extra width of double ones.

N

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9 hours ago, BEngo said:

I think you are right. A K11 (one panel with one set of fins) Stelrad  450 by 500 single rad will put out a bit over over  1000 BThU per hour. (Exactly how much depends on the air temperature, the boiler output temperature and how the rad is plumbed). You in effect have 5 (a total of 2500 mm rads 450 high)  of them so more than 5000  BThU/hr.  That is equivalent to  about 1.5 kW 

Allow for the pipes, and something for keeping the calorifier warm and you are up to 2-2.5kW.

 

I would replace your rads with K21 type (two panels one finned) which will take you  up to about 2.9 kW of rads plus pipes and will load the Ebby sufficiently that it does not short cycle, nor will it be flat out like a lizard drinking.

 

I assume your current rads live below the tunnels.  If so you will not notice the extra width of double ones.

N

Thank you, this is really helpful! 
Hopefully last question - do you recommend putting in a balance valve before it goes through the calorifier?

canalboat.co.uk suggest it helps a boat heat up quicker.

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Assuming the calorifier is in parallel with the rads and a two pipe system a balance valve as you call it on the calorifier circuit allows you to  alter the amount of hot water going through the calorifier. This allows you to ensure balance the whole system so each item that extracts heat receives the optimum amount of water and on one radiator or the calorifier takes more that it's fair share of the available heat. It will  probably also limit the amount of water flowing through the calorifier so when the calorifier is hot and thus taking no heat from the flow, less un-cooled (hot) water will be returned to the boiler. Even if the said balance valve is not used it is far easier to fit one when the system has been drained that after it is filled. Nearly any sort of valve that can be left in a partially closed position will do.

 

If you are redoing the system think about a valve that allows you to shut the rads down so you can use the boiler in the summer just to heat water. may be useful if you have a load of solar and don't need to run the  engine for charging or you suffer a breakdown.

 

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What Tony said about balance valves. All major components should have a full flow (no restriction to flow type, usually lever operated) valve either side of them so they can be removed without having to drain everything. Radiator valves do that for the rads. The boiler and the calorifier may need them added. Take the levers off (and put them somewhere safe)  so no one can accidentally shut them.

 

Whilst you are improving the heating set up, fit proper drain points for the rads and the calorifier if they do not have one.

 

If you run the Ebby for hot water only it needs to run for at least an hour at full output every time,  otherwise they tend to coke up. 

 

N

 

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Also buy some inhibited antifreeze for heating systems from screwfix and if Eber the same as a Webasto mix in a bucket with a 25% concentrate of antifreeze to water, then using a jug and funnel pour into the header tank. Important to mix first in bucket.

 

To work out your volume, you could fill your new system with just water and drain into buckets to work out the volume/litres of water. The rad valves you buy can have the drain valves built into them. I would replace the rad valves too as probably past it age wise. As said double panel single convector a good idea. If you have the space above could fit taller radiators than the original.

 

James.

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