Is it OK to fit taller radiators?

[Psycloud]

Hi All,

 

2 of the radiators on our boat have a leak in the bottom weld so I want to replace them, and while I'm at it I may aswell replace all 4 since they are all about 15 years old now. Currently they are all 500mm high single (K1) radiators but I am thinking of replacing with 600mm high ones, and slightly longer to account for the odd imperial lengths they are at present.

 

The boiler is an Eberspacher D5W and the total output for the 4 radiators would be 3.5kW so would the boiler be able to cope with this? With the old radiators (total 2.7kW) it seemed to cycle on and off every few minutes so perhaps the boiler was overpowered?

 

Also, I assume that as long as the header/expansion tank is higher than the top of the radiators it doesn't matter that the Eberspacher will be roughly in line with the top?

 

Many thanks

 

David

Edited August 17, 2014 by Psycloud

[pearley]

I would think the header tank would need to be a good few inches above the highest radiator to allow for expansion as the water heats up.

[Arthur Brown]

The expansion vessel will need to be above the rads and have enough expansion volume for the extra circulating fluid. The Eber should prefer being attached to the bigger rads.

[Psycloud]

The bottom of the header tank (outlet) will be at at least 4" above the top of the radiators (currently 8").

[Psycloud]

The current tank is what looks like an expansion from a car however I am looking to replace that with an allow 100mm x 200mm cylindrical one.

[pearley]

The current tank is what looks like an expansion from a car however I am looking to replace that with an allow 100mm x 200mm cylindrical one.

Mine is from a Renault and is about that size.

[smileypete]

How many kW is the Eberspacher?

 

The rads should match the output really, to prevent short cycling.

 

cheers, Pete.

~smpt~

Edited August 17, 2014 by smileypete

[Psycloud]

How many kW is the Eberspacher?

 

The rads should match the output really, to prevent short cycling.

 

cheers, Pete.

~smpt~

 

It's 5kW although we can open up the loop into the calorifier if needs be (we don't use that for hot water though as we have an gas boiler for instant).

I could stick to 500 high and just get a much longer one in the bedroom, currently 750mm, perhaps 1200mm which will bring it back to 3.5kW without reducing any head height.

 

I think really I'm just unsure about whether 4" is enough head height? If it is I can work with 600mm rads and keep the lengths shorter.

[smileypete]

What's the output on the low setting? When you say cycle off, do you mean it goes between high and low, or full off and back on?

 

Best to at least always keep some way above the low setting output, so it doesn't go through a full re-ignition regularly. Could consider using double rads where you most want the heat.

 

cheers, Pete.

~smpt~

[Psycloud]

Between low and high.

[NMEA]

A 3.5kw load is not enough for that boiler to function at its best, the thing to aim for is about 10 - 20% over the heaters rated capacity in order to reduce cycling and premature coking up. Could you fit double panel type 22 at one or more locations? Personally I would scrap the header and install a pressure loop with expansion vessel PRV and auto bleed pot if I were you as it can be fitted anywhere and makes bleeding a lot easier and I have far less trouble with pressurised systems than headers, it really is not possible to get a decent head of pressure with a header tank given the restrictions of a narrowboat. If you (or anybody else) wants to keep a header system and need a decent header I have a few that I remove from the kits as I never use them now, they are the sealed in at the top out of the bottom Webasto type so at least some pressure is built up unlike the open to atmosphere type.

[smileypete]

Between low and high.

 

Agree with NMEA, but probably not so bad nowadays with cleaner diesel, especially if DIY servicing can be done to keep an eye on things.

 

If it starts to coke up, one way of helping keep it clean is run some paraffin though now and then, though coking may also be a symptom of other problems.

 

cheers, Pete.

~smpt~

Edited August 17, 2014 by smileypete

[Psycloud]

A 3.5kw load is not enough for that boiler to function at its best, the thing to aim for is about 10 - 20% over the heaters rated capacity in order to reduce cycling and premature coking up. Could you fit double panel type 22 at one or more locations? Personally I would scrap the header and install a pressure loop with expansion vessel PRV and auto bleed pot if I were you as it can be fitted anywhere and makes bleeding a lot easier and I have far less trouble with pressurised systems than headers, it really is not possible to get a decent head of pressure with a header tank given the restrictions of a narrowboat. If you (or anybody else) wants to keep a header system and need a decent header I have a few that I remove from the kits as I never use them now, they are the sealed in at the top out of the bottom Webasto type so at least some pressure is built up unlike the open to atmosphere type.

 

I'd rather stick with the Type 11's as they are slimline whereas the 22's will stick out quite a way. I think then I will go for 600mm high and try and install a pressure loop and PRV - do you have a link to somewhere I can see what I need (diagram)?

[smileypete]

Just a thought, DeanS is champing at the bit for a plumbing project. Wonder if he can come up with a way of using the calorifier as a thermal store?

 

cheers, Pete.

~smpt~

[NMEA]

 

I'd rather stick with the Type 11's as they are slimline whereas the 22's will stick out quite a way. I think then I will go for 600mm high and try and install a pressure loop and PRV - do you have a link to somewhere I can see what I need (diagram)?

Ok, if you are that restricted then what can you do, short of a buffer tank? if you PM me an email address I will send you a PDF copy of the Webasto marine install manual, it has good diagrams of various types of systems and discusses the merits of each quite plainly. Screwfix have a clearence at the moment with a kit that has all you would need to convert to pressure. http://www.screwfix.com/p/comap-expansion-vessel-12ltr/27587

[Psycloud]

Ok, if you are that restricted then what can you do, short of a buffer tank? if you PM me an email address I will send you a PDF copy of the Webasto marine install manual, it has good diagrams of various types of systems and discusses the merits of each quite plainly. Screwfix have a clearence at the moment with a kit that has all you would need to convert to pressure. http://www.screwfix.com/p/comap-expansion-vessel-12ltr/27587

 

Thanks - will email you shortly. Unfortunately I don't have a trade account so can't view that screwfix link :/

[NMEA]

 

Unfortunately I don't have a trade account so can't view that screwfix link :/

Just try entering 27587 in the Screwfix search pane, not sure if it is a trade only offer (I got 8 for stock) but I don't think so.

If that doesn't work then try searching for "Comap Expansion Vessel"

Edited August 17, 2014 by NMEA

[ditchcrawler]

Just try entering 27587 in the Screwfix search pane, not sure if it is a trade only offer (I got 8 for stock) but I don't think so.

If that doesn't work then try searching for "Comap Expansion Vessel"

I went to http://www.screwfix.com/search?search=27587 and got a list of bits some of which you would need. But this may be a better link http://www.screwfix.com/p/expansion-vessel-12ltr/46517

Edited August 18, 2014 by ditchcrawler

[NMEA]

I went to http://www.screwfix.com/search?search=27587 and got a list of bits some of which you would need. But this may be a better link http://www.screwfix.com/p/expansion-vessel-12ltr/46517

It is worth searching for the Comap offer if you can get one though, only £54 for everything you need, and a free insulated coffee mug to boot!

Edited August 18, 2014 by NMEA

[Psycloud]

Thank you for the additional replies.

 

I've started the project, 3 of the 4 rads are installed, had to moved all the pipework as the old rads were imperial sizes and the new ones are all 50mm longer (I could have gone 50mm shorter but didn't see the point really), still using the old car header tank for the moment, but fired it all up yesterday evening and all working very well - you can actually feel the heat radiating off them whereas the old ones you could barely feel it - probably due to all the sludge they'd accumulated.

 

I am looking into the pressure loop option... Would this be an OK kit rather than the £55 at screwfix? http://www.ebay.co.uk/itm/PRESSURE-VESSEL-SEALED-SYSTEM-EXPANSION-KIT-FILLING-LOOP-RELIEF-VALVE-GAUGE-SET-/370834707990?pt=UK_Home_Garden_Hearing_Cooling_Air&hash=item5657789616

[NMEA]

Its fine but you would need a pressure vessel and a mounting cradle which would bump up the price, perhaps beyond the Screwfix complete kit which as I said, has all you need.

[Psycloud]

Its fine but you would need a pressure vessel and a mounting cradle which would bump up the price, perhaps beyond the Screwfix complete kit which as I said, has all you need.

 

Try as I might, I cannot get to the complete kit option on Screwfix, even searching the number and the description Grrr

 

Out of interest, why 12ltr and not say 8ltr? Given that the current header is only about 2ltrs and doesn't overflow I'm wondering what 12ltr gives me over 8ltr?

 

If I can't get the Screwfix option then this might be a suitable alternative? http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=400328526688&var=670043618045&fromMakeTrack=true&ssPageName=VIP:watchlink:top:en

Edited August 19, 2014 by Psycloud

[NMEA]

Why not just call the Screwfix freephone number and quote the stock number I quoted, and see what happens?

[smileypete]

If I can't get the Screwfix option then this might be a suitable alternative? http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=400328526688&var=670043618045&fromMakeTrack=true&ssPageName=VIP:watchlink:top:en

 

Looks pretty reasonable. Here's a pic of one way to install, plenty of examples on Google images:

 

 

Worth making sure there's a double check valve on the cold feed to the calorifier. That way there's no chance that any antifreeze leaking into the calorifier can work it's way back into the drinking water supply.

 

Also make sure the rads are balanced (google radiator balancing) or the heater may cycle much more than it needs to.

 

The existing expansion bottle may be too small to work OK in all conditions, unless the system volume and volume between the marks in the bottle is known. A commercial breakers may supply a big one cheap if asked nicely.

 

cheers, Pete.

~smpt~

Edited August 19, 2014 by smileypete