Redirecting hot water to rads via stop cock

[Kristian]

OK I've a 70 ft nb with full central heating via a Kabola E5 series boiler, the water tank/calorifier gets very hot and gives me all the hot water I could ever need, almost to the point where the water is too hot, however the radiators don't really get hot but just warm, I'm guessing the water via the circulation pump takes the route with the least resistance hence I'm getting lots of really hot water and only warm radiators.

The hot water pipe that comes from the boiler goes under the floor to a Hep "T" where the hot water goes in two directions, left to the calorifier to give me hot water and to the right in the other direction which is the feed to the heating system via rads.

Can anyone see an issue with putting with putting a stop cock between the calorifier and the Hep T? That way all the hot water from the boiler has to go into the rads?

Im just thinking about another very cold winter coming and after the water tank has got its hot water close the stop cock and let the boiler concentrate all its efforts on heating the radiators..

Many thanks Kristian..

[David Schweizer]

 

OK I've a 70 ft nb with full central heating via a Kabola E5 series boiler, the water tank/calorifier gets very hot and gives me all the hot water I could ever need, almost to the point where the water is too hot, however the radiators don't really get hot but just warm, I'm guessing the water via the circulation pump takes the route with the least resistance hence I'm getting lots of really hot water and only warm radiators.

The hot water pipe that comes from the boiler goes under the floor to a Hep "T" where the hot water goes in two directions, left to the calorifier to give me hot water and to the right in the other direction which is the feed to the heating system via rads.

Can anyone see an issue with putting with putting a stop cock between the calorifier and the Hep T? That way all the hot water from the boiler has to go into the rads?

Im just thinking about another very cold winter coming and after the water tank has got its hot water close the stop cock and let the boiler concentrate all its efforts on heating the radiators..

Many thanks Kristian..

 

 

I have modified the primary hot water circuit on our boat so that the water can either be directed to the calorifier or the radiators, or both (or neither) and it works fine, One consideration needs to be where the expansion/overflow tank is connected. On our boat any expansion when the radiators are off is into the Bowman tank on the engine, and any expansion when the calorifier is off, is into a small expansion tank above the forward radiator (inside a cupboard). I should however point out that we have a single coil calorifier so the water feeding the radiatiors is the same water as that which is circulation round the engine etc. Another point to consider is ensuring that the gate valves are full bore, as many are not. Full bore ball valves would be better, and in my experience are more reliable.

 

Having said all that we still have some difficulty in persuading the top far end of the forward radiator to heat up, and it has been suggested this may be because of restricted flow through the standard domestic radiator valves, which have a smaller bore than the pipe feeding them. If you have a similar set up, this may also be contibuting to the poor flow into your radiators. One of my jobs for the winter is to replace the radiator valves with full bore ball valves which will increase the flow area by more than 100%,

Edited December 7, 2013 by David Schweizer

[Hawkmoth]

What sort of pump do you have on the system? Have you tried any way of re-directing the flow to the rads?

It might be worth considering putting a globe valve or indeed any valve that can be turned down, instead of a ball valve. Globe valves can be turned down (throttled) to control the flow to the calorifier instead of shutting it off entirely. Ball valves don't like being used partially open, they should be either open or shut.

Bob

[Tony Brooks]

In my view the calorifier circuit should be treated just like a rad and have a lock shield valve on it at least so the whole system can be balanced (sounds like yours may not be - cue MtBM). As has been said, as long as you do not isolate any vent or heater tank it should be fine to use such a valve. Think for the moment about getting hot water in the summer, you might want a valve that will allow you to select either or both.

[ackdaw]

Another point to consider is ensuring that the gate valves are full bore, as many are not. Full bore ball valves would be better, and in my experience are more reliable.

 

thats correct or whats called a gate vavle , if one looks down a ballvalve type stop tap on a 15 mm ballvavle the actual hole through the vavle is mininmal 6or 8 mm etc so it may be best to fit a 22mm ball vale on a 15 mm pipe to as such get the better flow rate , how ever a gate vavle tend to open and allow full bore , so a stop taps not recomended a ball vavle go 22 mm and a gate valve size same as the pipe work .

[by'eck]

 

OK I've a 70 ft nb with full central heating via a Kabola E5 series boiler, the water tank/calorifier gets very hot and gives me all the hot water I could ever need, almost to the point where the water is too hot, however the radiators don't really get hot but just warm, I'm guessing the water via the circulation pump takes the route with the least resistance hence I'm getting lots of really hot water and only warm radiators.

The hot water pipe that comes from the boiler goes under the floor to a Hep "T" where the hot water goes in two directions, left to the calorifier to give me hot water and to the right in the other direction which is the feed to the heating system via rads.

Can anyone see an issue with putting with putting a stop cock between the calorifier and the Hep T? That way all the hot water from the boiler has to go into the rads?

Im just thinking about another very cold winter coming and after the water tank has got its hot water close the stop cock and let the boiler concentrate all its efforts on heating the radiators..

Many thanks Kristian..

 

 

Basically what I have with a Mikuni. The hot water output feeds a "T" piece, left to calorifier loop right to three radiator circuit. There are stop valves each side of this "T" which control the flow. My builder removed the valve wheel on the radiator circuit (having optimised the flow) but left the calorifier one to fine tune my hot water to radiator heating requirements.

[nicknorman]

If you have TRVs maybe you should remove them, they can be a bit restrictive. You probably need to turn down the flow on the near radiators using its lock shield valve, to equalise the flow to all the rads, and install some means of throttling or even stopping the flow to the calorifier as you have suggested. I have the same T with 2 gate valves as By'eck but I put wheels on both of them, so I can have hot water only, rads only, or both. I just have to be careful with hot water only as the calorifier can't absorb the mikuni's output for long (I tend to crack open the radiator circuit just enough to keep the Mikuni fired). It heats the water in no time!

[bottle]

 

I have modified the primary hot water circuit on our boat so that the water can either be directed to the calorifier or the radiators, or both (or neither) and it works fine, One consideration needs to be where the expansion/overflow tank is connected. On our boat any expansion when the radiators are off is into the Bowman tank on the engine, and any expansion when the calorifier is off, is into a small expansion tank above the forward radiator (inside a cupboard). I should however point out that we have a single coil calorifier so the water feeding the radiatiors is the same water as that which is circulation round the engine etc. Another point to consider is ensuring that the gate valves are full bore, as many are not. Full bore ball valves would be better, and in my experience are more reliable.

 

Having said all that we still have some difficulty in persuading the top far end of the forward radiator to heat up, and it has been suggested this may be because of restricted flow through the standard domestic radiator valves, which have a smaller bore than the pipe feeding them. If you have a similar set up, this may also be contibuting to the poor flow into your radiators. One of my jobs for the winter is to replace the radiator valves with full bore ball valves which will increase the flow area by more than 100%,

 

 

Have you balanced your radiators, assuming it is two pipe system, the in and out of the radiators go to different pipes and not in one end and out the other to the next radiator

 

If you do have a two pipe system then the temperature drop from the in to the out should be in the region of 10° C.

 

The in should be fully open and the out adjusted to obtain this temperature drop, maybe nearly fully closed.

 

Friend had never had his done and the radiator at the front of the boat never got warm, I adjusted as above and voilà a hot radiator.

[nb Innisfree]

When balancing rads the one furthest fron the boiler and therefore the highest resistance should have both valves fully open and the rest of the rads progressively turbed down in order of resistance. Easiest way to tell is to fully open all rad valves and feel the temp, coolest is the one furthest away.

[David Schweizer]

Another point to consider is ensuring that the gate valves are full bore, as many are not. Full bore ball valves would be better, and in my experience are more reliable.

 

thats correct or whats called a gate vavle , if one looks down a ballvalve type stop tap on a 15 mm ballvavle the actual hole through the vavle is mininmal 6or 8 mm etc so it may be best to fit a 22mm ball vale on a 15 mm pipe to as such get the better flow rate , how ever a gate vavle tend to open and allow full bore , so a stop taps not recomended a ball vavle go 22 mm and a gate valve size same as the pipe work .

 

There are several types of ball valve, the type you are descibing is opened/closed with a screwdreiver, and is as you say usually about half the diameter of the supply pipe. Ball valves which are opened/closed with a lever or butterfly are almost always full bore, and are described as such. Asc far as gate valves are concerned there seems to be no standard, some are aproaching full bore, whilst others are much smaller.

 

 

Have you balanced your radiators, assuming it is two pipe system, the in and out of the radiators go to different pipes and not in one end and out the other to the next radiator

 

If you do have a two pipe system then the temperature drop from the in to the out should be in the region of 10° C.

 

The in should be fully open and the out adjusted to obtain this temperature drop, maybe nearly fully closed.

 

Friend had never had his done and the radiator at the front of the boat never got warm, I adjusted as above and voilà a hot radiator.

 

Yes we have a a two pipe system, but there are only two radiators on our boat, both 12" high. The one closest to the boiler is about 15" long whilst the one furthest away is more than 4ft long. Balancing the smaller one, or even isolating it, has no impact on the temperature of the larger one, balancing the larger one does nopt work either. I have come to the vioew that there is either insufficient flow through the radiator valves, or that that the radiator is actually too long for the amount of pressure available.

Edited December 7, 2013 by David Schweizer

[AndrewIC]

Replace the T piece with a "T-port valve", then you can have either or both?

[bottle]

David

 

Niow clutching at straws and I expect you have done this, bled the last radiator to eliminate an air lock.

[smileypete]

 

Having said all that we still have some difficulty in persuading the top far end of the forward radiator to heat up, and it has been suggested this may be because of restricted flow through the standard domestic radiator valves, which have a smaller bore than the pipe feeding them. If you have a similar set up, this may also be contibuting to the poor flow into your radiators. One of my jobs for the winter is to replace the radiator valves with full bore ball valves which will increase the flow area by more than 100%,

 

What sort of boiler do you have and does the problem occur if both the calorifier and small rad are isolated, and the lockshield and rad valves on the bigger rad are fully open?

 

If the boiler is chucking out heat it has to go somewhere, it can't just disappear. If it's a backboiler and the stove is ticking over then much of the heat may be lost from the pipes and decent lagging would help.

 

 

Another alternative to a lever type ball valve is the ballofix type which is like a screwdriver operated valve with much wider bore than the standard isolator:

 

 

http://www.toolstation.com/shop/Plumbing/Valves/Full+Bore+Isolating+Valve+CP+15mm/d20/sd2696/p11495

 

Using a ball valve part open can damage the seal apparently and stop it sealing 100% but that may be OK on something like a boat calorifier where pressure are low and it's not needed for isolation.

 

Cheap washing machine valves sometimes don't seal 100% when closed after a long period, can be a little nerve wracking at first but they usually stop leaking after a while

 

cheers, Pete.

~smpt~

Edited December 9, 2013 by smileypete

[David Schweizer]

David

 

Niow clutching at straws and I expect you have done this, bled the last radiator to eliminate an air lock.

 

Yes It has been bled and I have learnt how to get rid of air locks, it is a complicated procedure which involves releasing the pressure on the header tank and bangng the radiator with the palm of my hand.

[David Schweizer]

 

What sort of boiler do you have and does the problem occur if both the calorifier and small rad are isolated, and the lockshield and rad valves on the bigger rad are fully open?

 

If the boiler is chucking out heat it has to go somewhere, it can't just disappear. If it's a backboiler and the stove is ticking over then much of the heat may be lost from the pipes and decent lagging would help.

 

cheers, Pete.

~smpt~

 

The boiler is an Ellis Heatmaster, the radiatotr valves/lockshields are fully open, and there is no problem with heat reaching the radiator, all the pipes are fully lagged with thick walled closed cell pipe lagging. The radiator does heat up, it is just that the top corner (furthest from the boiler) gets barely warm, it is the same on either the boiler or with direct heat from the engine, and with both calorifier and smaller radiator closed off.

 

The problem radiator is a double and quite large at 56" long x 11" high. The other radiator, which is also double and closer to the boiler, is about 15" long x 11" and high gets very hot across it's whole surface, I am going to try fitting full bore valves in an attempt to increase flow, but I still wonder whether a shorter radiator might be more effective.

 

When the heating system is worked from the engine it is obviously pumped by the engine coolant pump, but when it is on the boiler it works by convection, and the system has been installed in compliance with the Elliis Heatmaster instalation instructions. The only significant difference between boiler and engine feed is that on the boiler the calorifier takes much longer to heat up than the radiators.

 

Edit to your edit:- Unless the Ballofix valve illustrated is different to all the other slot operated ball valves I have ever seen, my experience suggests that they are of a much reduced bore than the full bore lever or butterfy ball valves. I also do not intend to use them part open/closed, they will either be open or closed, I have others in the system for isolation and have not experienced any leakage problems, and I would not even contemplate using a washing machine tap for very hot water, and anyway they do not have compression fittings at both ends.

 

These are the types of full bore ball valves i intend to use :-

 

 

Edited December 9, 2013 by David Schweizer

[nb Innisfree]

How high are your rads mounted? If they are only 11" tall and mounted low down it will struggle to circulate without a pump? If so raising the rad may improve circulation.

[David Schweizer]

How high are your rads mounted? If they are only 11" tall and mounted low down it will struggle to circulate without a pump? If so raising the rad may improve circulation.

 

Higher than the boiler output tapping, and our boat is much higher at the font than the back m, so taking that into account, the top of the radiator is about 15" higher than the boiler tapping.

 

All that apart, the problem also occurs when the water is being pumped.

Edited December 9, 2013 by David Schweizer

[smileypete]

OK, as a sanity check; if the boat tilts bow to stern then I wonder if air could accumulate there if it's the highest point?

 

IF it is indeed bled alright do you know the rated output of the heatmaster to water in kW? A double finned rad of that size should require about 1.2kW, if the heat source is lower it'll won't heat up as much. Of course a smaller rad will get hotter

 

Finally which tappings are used for flow and return, the two bottom ones, and is it pumped or gravity? If the adjacent tappings are used the water might be tanking a short cut on a long squat and the rad getting heated unevenly.

 

cheers, Pete.

~smpt~

Edited December 9, 2013 by smileypete

[nb Innisfree]

 

Higher than the boiler output tapping, and our boat is much higher at the font than the back m, so taking that into account, the top of the radiator is about 15" higher than the boiler tapping.

 

All that apart, the problem also occurs when the water is being pumped.

Sorry I misread your post as saying it worked when on engine pump.

If as Pete suggests air is trapped at the highest point -being the top corner of rad?- maybe an auto air valve at this point might do the biz. I have used auto air valves with great succes at home and on the boat, very simple and reliable and never leaked in many years of use.

[David Schweizer]

OK, as a sanity check; if the boat tilts bow to stern then I wonder if air could accumulate there if it's the highest point?

 

IF it is indeed bled alright do you know the rated output of the heatmaster to water in kW? A double finned rad of that size should require about 1.2kW, if the heat source is lower it'll won't heat up as much. Of course a smaller rad will get hotter

 

Finally which tappings are used for flow and return, the two bottom ones, and is it pumped or gravity? If the adjacent tappings are used the water might be tanking a short cut on a long squat and the rad getting heated unevenly.

 

cheers, Pete.

~smpt~

 

Air could accumulate (as in all radiators) but it is bled and checked routinely. The output from the boiler is about 5Kw so more than adequate, The feed is into the top of the radiator (closest to the boiler), and return is at the bottom (furthest from boiler) on a two pipe circuit. Circulation is pumped when on the engine, and by convection when on the boiler, the pipes from the boiler are 28mm, all as specified by Ellis Restorations (Heatmaster)

Edited December 9, 2013 by David Schweizer

[Kristian]

OK Folks many thanks for your input, ive really got some ideas going around in my swede now.

Just to let you all know its a pumped system and yes all rads have been balanced and bled...

 

Kristian.....even more thoughts would be great....

[koukouvagia]

I've used a combination of ballofix for aesthetic reasons and gate valves where they're tucked away out of sight. (The header tank is not shown on the diagram - it's just near the pump). Works perfectly. I do find that I need to get the water circulating round the system for a few minutes before turning on the large radiator, though.

To heat radiator and calorifier together: a,c,e open; b,d closed (as diagram - normal winter setting once the cabin has heated up)

To heat radiator only: a,c,d open; b,e closed (for rapid heating up of the cabin)

To heat calorifier only: b,e open; a,c,d closed (used in the summer when I don't need radiator)

This arrangement gives me the flexibility of either heating the radiator alone or the calorifier alone or both radiator and calorifier together.

However, I have to get this diagram out whenever I change over from winter to summer settings, since I can never remember how I set the system up!

[David Schweizer]

Sorry I misread your post as saying it worked when on engine pump.

If as Pete suggests air is trapped at the highest point -being the top corner of rad?- maybe an auto air valve at this point might do the biz. I have used auto air valves with great succes at home and on the boat, very simple and reliable and never leaked in many years of use.

 

I have considered installing an auto bleed valve, but have always worried that they might start leaking whist the boat is unattended, I know they are automatic, but can they be locked closed as well?

 

I've used a combination of ballofix for aesthetic reasons and gate valves where they're tucked away out of sight. (The header tank is not shown on the diagram - it's just near the pump). Works perfectly. I do find that I need to get the water circulating round the system for a few minutes before turning on the large radiator, though. < snip

 

 

You think that is complicated Jim? You want to see the system on our boat. It is fairly obvious when looking into the calorifier cupboard, where they are all located, but I do have stickers on the walls which helps to indicate which valve does what, colour coded levers helps.

Edited December 9, 2013 by David Schweizer

[smileypete]

David,

 

If the heatmaster works by gravity then I'd have full bore valves on the rad, not standard rad valves and lock shields, might even need to use both top radiator tappings and both bottom ones as well.

 

Also how far between heat master and most distant rad? If it's a long way it might be better to add a pump to improve circulation, would help when running the engine too. Does the engine operate via some sort of heat exchanger?

 

Either the heatmaster is cycling on and off or heat is being lost from the pipes, 5kW has got to go somewhere.

 

ETA: The automatic 'bottle vents' do have a little cap on top that can be screwed shut, try a google image search for 'bottle vent'

 

cheers, Pete.

~smpt~

Edited December 9, 2013 by smileypete

[dor]

I've got 22mm full flow lever ball valves in the flow so I can select HW, heating or both. A small rad in the bathroom is always on so there is a load if both valves are inadvertently closed and also warms up the bathroom when only hot water is selected.

 

Is simple and all works very well. I did think of putting a motorised valve in, but 12V ones were not easy to find and those that I did find were expensive.