Rayburn and water heating.

[ThePhoenix]

Hi, seeking some advice on a Rayburn and control of hot water.

Leaving out a very long story, my mothers house is about 200 miles away from me and she has recently moved into a care home. My brother and I need to renovate this from afar in order to rent it out to help with funds for her ongoing care.

I have never really shown very much notice in how this Rayburn integrates with the heating in the house, but now I have to show an interest. From an initial visit and dig around in the pipework it seems to me that there is a gas boiler providing central heating and controlled hot water via an indirect vented cylinder. The Rayburn is also gas-fired and seems to be feeding a secondary coil in the hot water tank via a pair of large (28mm?) pipes. I am assuming that this is a simple gravity-fed heating loop. First question: does what I have suggested here sound like any sort of typical installation, or am I maybe missing something?

The Rayburn is currently out of commission (no safety cert, as insufficient ventilation - another issue that needs sorting), but once it is up and running I can see no way of controlling the temperature of the hot water. Is that also normal for Rayburns? I guess that they are designed so that the water in the heating circuit never boils? It should now becoming apparent just how little I know about these things .

If all of the things I believe to be true are, and I wish to control the temperature of the hot water in the tank, can I install another zone valve in the Rayburn heating loop, electrically wired in parallel with the one controlling the boiler's hot water coil, or will bad things happen if I inhibit this flow?

Thanks for any advice.

 

[SJB060685]

I'm not gas certified, so to be double sure you would need to talk to a gas engineer familiar with Rayburn. However I'm an oil burner technician by trade and more than familiar with Rayburn's running on oil.
The two 28mm primaries are for the gravity circulation as you say. Rayburn's on oil require a cylinder of minimum capacity, 190-200 litres I believe and a heat sink radiator to dump any additional heat. This should in theory keep to temperature of the water at or around 60°c. Again you'd need to check with a gas engineer familiar with gas Rayburn's to be sure of the requirements.
Do not add additional valves etc to the system, which may impede the cookers chance to disapate heat. When set up correctly they will mosey along perfectly without excessive hot water temperatures.

 

[ThePhoenix]

Thank you SJB060685, that is great info.

I take on board what you say about needing to check with a gas guy (and hopefully there will be one along in a while ), but I imagine oil is not that much different in this configuration, and if the radiator you are talking about his just a standard radiator in one of the rooms, I don't think there is one in this circuit. And the tank is nothing like 190l - it's small, more like 130/140

With your advice in mind I will take a very good look around next time I am there, and definitely won't be toying with installing any valves.

One other thing. I want to (need to, it seems!) increase the size of the tank. Will any "standard" twin-coil tank do, or is there something particular required for a Rayburn?

Cheers.

 

[SJB060685]

Just a decent make foam lagged twin coil open vented copper cylinder. The requirements for oil are probably the same, if not close to that of a gas cooker but again you would need to go through this with someone familiar with them and has the tickets. Knowing what I do about oil burners then Id say a heat sink radiator of adequate size is needed but your engineer can guide you further. I can't be too much more help and unfortunately I'm not aware of any engineer on this forum with the tickets and knowledge for gas Rayburn's to advise further. In fact there's only a few of us on here with the knowledge and experience with oil fired cookers.

 

[ThePhoenix]

Just a decent make foam lagged twin coil open vented copper cylinder. The requirements for oil are probably the same, if not close to that of a gas cooker but again you would need to go through this with someone familiar with them and has the tickets. Knowing what I do about oil burners then Id say a heat sink radiator of adequate size is needed but your engineer can guide you further. I can't be too much more help and unfortunately I'm not aware of any engineer on this forum with the tickets and knowledge for gas Rayburn's to advise further. In fact there's only a few of us on here with the knowledge and experience with oil fired cookers.

That's all been very helpful. Thanks for taking the time.

 

[exedon2]

I was for many years a agent for Stanley cookers (all fuels) but we did deal with most makes of this type of cooker.
To advise exactly as there are so many different rayburns can you let us know what model you have?
Picture of data plate would be useful.
Some rayburn are thermostatic controlled in hot water mode others not although all will produce higher temperature hot water when used for cooking hence the need for correct sized cylinder and heat leak radiator.

 

[ThePhoenix]

I was for many years a agent for Stanley cookers (all fuels) but we did deal with most makes of this type of cooker.
To advise exactly as there are so many different rayburns can you let us know what model you have?
Picture of data plate would be useful.
Some rayburn are thermostatic controlled in hot water mode others not although all will produce higher temperature hot water when used for cooking hence the need for correct sized cylinder and heat leak radiator.

I am not with the cooker at the moment and will not be for a few weeks yet, but with reference to some photo's I have, knowing the approx year that it was commissioned and with reference to some online information, I am thinking it is likely a Rayburn Royal G7 (will obviously confirm this when I next visit). The spec says that this is a 2.6 kW/hr ( 9000 BTU/Hr) unit for use with a storage cylinder of 135 litres; not found any mention of a heat-sink radiator. This seems to tie in with what I was seeing and is exactly with what I estimated the size of the existing cylinder to be.

Confirmation of a few things outstanding for me, but now I am much more confident in what I am dealing with and, surprises aside, am now happy to proceed with the installation of the larger cylinder that I was planning and know not to mess about with incorporating any zone valves in the gravity-fed heating loop.

Cheers all.

 

[exedon2]

The G7 was first of purpose built gas Rayburns early 70s to mid 90s constantly burning appliance sort of a small aga.
No control of hot water temperature whatsoever.
Despite manufacturer recommending a 42 X 18 cylinder owners who either cooked a lot or used little hot water (or both) tended to have boiling problems .Hence why heat leak rads sometimes fitted. If a twin coil cylinder fitted tended to be even worse if other heat source was not turned off for hot water when Rayburn on.
As property will be rented maybe fit tmv3 blenders on hot taps and make sure shower is thermostatic .

 

[brum]

Thank you SJB060685, that is great info.

I take on board what you say about needing to check with a gas guy (and hopefully there will be one along in a while ), but I imagine oil is not that much different in this configuration, and if the radiator you are talking about his just a standard radiator in one of the rooms, I don't think there is one in this circuit. And the tank is nothing like 190l - it's small, more like 130/140

With your advice in mind I will take a very good look around next time I am there, and definitely won't be toying with installing any valves.

One other thing. I want to (need to, it seems!) increase the size of the tank. Will any "standard" twin-coil tank do, or is there something particular required for a Rayburn?

Cheers.

Heat loss radiator could well be in the loft have done this a few times just to site it somewhere

 

[ThePhoenix]

Hi all, it's been a long time since I visited this property and now have a more detail about the the heating system and am now hoping for a bit more advice.

I can confirm that the DHW cylinder is 135l and is heated by two sources: one a standard domestic gas boiler and the other a Rayburn Royal G7 (2.6 kW/hr/9000 BTU/Hr), using what I originally thought was a twin coil cylinder arrangement.

As it turns out this cylinder is not a twin coil. A coil is used for the gas boiler side, but the Raburn gravity feeds directly in and out of the body of the cylinder through two Essex flanges. I am no way a professional plumber but these flanges seem to have been installed by someone less talented than even I, who just happened to use the hole saw that he found in his toolbox at the time, as in my opinion the holes are way too big causing them to leak and damage the downstairs walls and some of the joists.

If I were to replace this cylinder with a (larger) twin coiled equivalent then I would have all of the issues of needing to provide a separate header tank and expansion pipework for the Rayburn circuit, which is not required with the system as it it currently configured. I don't want to do this if I don't have to, as for one thing this is a stone-built cottage and routing new pipework will be very difficult and the loft is hard to access with insubstantial joists. And remember all I am trying to achieve here is getting the system in a position where I can fire the Rayburn up, have it producing local warmth and a cooking ability in the kitchen and not be standing around as just an ornament. Its DHW heating efficiency/ability is not a concern.

The issue I have is putting Essex flanges in a brand new cylinder as I don't consider them to be a robust solution. Am I wrong?

My main question is this; is it possible to order cylinders with flanges already brazed/soldered/whatever as specified by a customer, and if so what would be the cost of such a provision be, versus the cost of having to install an expansion solution, header tank and all the associated pipework that that would entail?

Is there any other solution that I haven't considered?

Thanks all.

 

[exedon2]

First I would strongly recommend a twin coil cylinder with both coils indirect, correct way to do it .
Easy enough to have a bespoke cylinder made .
I use Newark cylinders for special cylinders mostly because I can collect from them rather than pay carriage. They will make a cylinder in any configuration you like choice of copper or stainless.

 

[JC22024]

Why not take the Rayburn out and take the opportunity to install a new cylinder with electric immersion and coil from gas boiler?

 

[ThePhoenix]

First I would strongly recommend a twin coil cylinder with both coils indirect, correct way to do it .
Easy enough to have a bespoke cylinder made .
I use Newark cylinders for special cylinders mostly because I can collect from them rather than pay carriage. They will make a cylinder in any configuration you like choice of copper or stainless.

Thank you for the advice and I would agree with what you say about the the secondary indirect coil. The thing is that this is a listed stone building and getting permissions, running new pipework and finding spaces for header tanks etc is nigh on Impossible. The Newark Cylinders tip is very useful thank you and I have mailed them for some costs. Thanks again.

 

[ThePhoenix]

Why not take the Rayburn out and take the opportunity to install a new cylinder with electric immersion and coil from gas boiler?

Unfortunately for me this is a listed building and the Rayburn is a feature of the kitchen. The existing cylinder is already coiled up to a gas boiler and it has an immersion heater, so there is no problem with hot water (apart from the leaking Essex flanges, of course). My only goal here is to get the minimum amount plumbed in to a replacement cylinder in order to be able to turn the Rayburn on, so that it can work as both a cooker and a heat source for the kitchen.

This is all based on my understanding that it is not possible to run a Rayburn without its boiler being plumbed in and filled. If it is possible to have the boiler section removed or modified in some way as to not being required at all I would be happy with that as a solution also?