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HOW TO DRAIN SEALED CENTRAL HEATING SYSTEM
Hi,
Wondering if anyone could help with the above. I have a sealed central heating system(as far as i know) with a combi 80 potterton boiler. I want to drain system and clean with fernox then add inhibitor. I know how to fill it back up i'm just unsure how to drain it. I've had plumbers in before who have drained it in a matter of seconds. Is there some valve inside boiler somewhere? Boiler is about 8 years old now and some rads even older although replacing room by room when decorating. Unsure if anything has been added to system before but it's been drained and refilled quite a bit recently so thought I'd better add something. Any tips greatly appreciated. |
HOW TO DRAIN SEALED CENTRAL HEATING SYSTEM
wrote:
Wondering if anyone could help with the above. I have a sealed central heating system(as far as i know) with a combi 80 potterton boiler. I want to drain system and clean with fernox then add inhibitor. I know how to fill it back up i'm just unsure how to drain it. I've had plumbers in before who have drained it in a matter of seconds. There should be drain cocks at the lowest point(s) of the system (something like this: http://www.screwfix.com/app/sfd/cat/...3349&ts=21170). Connect a hosepipe to the output and open the valve at the end. You'll need to open the bleed valves on the radiators (starting with upstairs!) to release the vacuum formed inside the system to allow the water to flow out. Oh, and when you're refilling later, don't do what I did at the weekend. Having drained down, I removed the threaded plug from the end of the bathroom towel rail to pour in my inhibitor, and then replaced it, taking care it was sealed nice and tight. Went back to the boiler and refilled the system; 5 minutes later going round checking I found water pouring down the wall below the bathroom. Although I'd replaced the plug in the towel rail, I'd forgotten that the bleed valve built into the plug was still open. Oops. And to add insult to injury, because the towel rail control valve happened to be closed at the time, I had effectively flushed out of the bleed valve the contents of the towel rail - ie, the entire dose of inhibitor! :-( David |
HOW TO DRAIN SEALED CENTRAL HEATING SYSTEM
Lobster wrote: wrote: Wondering if anyone could help with the above. I have a sealed central heating system(as far as i know) with a combi 80 potterton boiler. I want to drain system and clean with fernox then add inhibitor. I know how to fill it back up i'm just unsure how to drain it. I've had plumbers in before who have drained it in a matter of seconds. There should be drain cocks at the lowest point(s) of the system (something like this: http://www.screwfix.com/app/sfd/cat/...3349&ts=21170). Connect a hosepipe to the output and open the valve at the end. You'll need to open the bleed valves on the radiators (starting with upstairs!) to release the vacuum formed inside the system to allow the water to flow out. Oh, and when you're refilling later, don't do what I did at the weekend. Having drained down, I removed the threaded plug from the end of the bathroom towel rail to pour in my inhibitor, and then replaced it, taking care it was sealed nice and tight. Went back to the boiler and refilled the system; 5 minutes later going round checking I found water pouring down the wall below the bathroom. Although I'd replaced the plug in the towel rail, I'd forgotten that the bleed valve built into the plug was still open. Oops. And to add insult to injury, because the towel rail control valve happened to be closed at the time, I had effectively flushed out of the bleed valve the contents of the towel rail - ie, the entire dose of inhibitor! :-( David David, Thanks for reply. I'll go and have a look for the valve. Would it actually be inside the boiler? As I've said plumbers have drained system before and they seem to have front cover off at the time and do not connect any hose etc. Unless I have a hose on there already. |
HOW TO DRAIN SEALED CENTRAL HEATING SYSTEM
Lobster wrote: wrote: Lobster wrote: wrote: Wondering if anyone could help with the above. I have a sealed central heating system(as far as i know) with a combi 80 potterton boiler. I want to drain system and clean with fernox then add inhibitor. I know how to fill it back up i'm just unsure how to drain it. I've had plumbers in before who have drained it in a matter of seconds. There should be drain cocks at the lowest point(s) of the system (something like this: http://www.screwfix.com/app/sfd/cat/...3349&ts=21170). Connect a hosepipe to the output and open the valve at the end. You'll need to open the bleed valves on the radiators (starting with upstairs!) to release the vacuum formed inside the system to allow the water to flow out. I'll go and have a look for the valve. Would it actually be inside the boiler? As I've said plumbers have drained system before and they seem to have front cover off at the time and do not connect any hose etc. Unless I have a hose on there already. There may well be a draining point within the boiler, however that shouldn't be the only place. Unless your boiler is mounted at floor level(!), if you drain from there you will leave everything below the drain point (ie, the whole downstairs heating system, if the boiler's downstairs) full of water. Hence the need for drain cocks at the lowest point on the system (may even be built into the lockshield valves at the ends of the radiators. If there's more than one 'low point' (eg if the ground floor's solid and each if your downstairs radiators is fed from a 'loops' of pipe dropped down from the first floor, then each such 'loop' should have a drain point. That being said, it's unfortunately very commonplace for these to be left off the system altogether by the cheapskate/idle heating engineer who installed the system, so don't be too surprised if you can't find it/them! If you can't, then you basically have to gradually undo a coupling at a radiator valve, and collect the water which comes out - takes a long time and may well be messy. Do you really need to do it? And then you fit a drain cock before refilling....! I certainly can't see how plumbers can have actually drained the system before from your description - what task were they doing at the time? David No I don't really need to do it but I'd like to give it a flush and put in inhibitor. Plumbers were in fixing leaky radiators both upstairs and downstairs I think and I'm 99.9% positive they drained from inside boiler(should've asked them when they were in). I can get under the floor but they definitely didn't go under there to drain it down. Boiler is on wall in kitchen at height of wall cupboards in the floor cupboard beneath boiler I have the filling loop. I've took front cover off boiler and can't see anything that looks like screwfix picture link. I'm doing up kitchen at the moment and will be replacing old rad which I'll be able to manage. So I was intending putting in fernox flush while fitting new rad but then I've still got the problem that this will need drained and then flushed a couple of times before adding inhibitor. Cheers |
HOW TO DRAIN SEALED CENTRAL HEATING SYSTEM
wrote in message oups.com... Lobster wrote: wrote: Lobster wrote: wrote: Wondering if anyone could help with the above. I have a sealed central heating system(as far as i know) with a combi 80 potterton boiler. I want to drain system and clean with fernox then add inhibitor. I know how to fill it back up i'm just unsure how to drain it. I've had plumbers in before who have drained it in a matter of seconds. There should be drain cocks at the lowest point(s) of the system (something like this: http://www.screwfix.com/app/sfd/cat/...3349&ts=21170). Connect a hosepipe to the output and open the valve at the end. You'll need to open the bleed valves on the radiators (starting with upstairs!) to release the vacuum formed inside the system to allow the water to flow out. I'll go and have a look for the valve. Would it actually be inside the boiler? As I've said plumbers have drained system before and they seem to have front cover off at the time and do not connect any hose etc. Unless I have a hose on there already. There may well be a draining point within the boiler, however that shouldn't be the only place. Unless your boiler is mounted at floor level(!), if you drain from there you will leave everything below the drain point (ie, the whole downstairs heating system, if the boiler's downstairs) full of water. Hence the need for drain cocks at the lowest point on the system (may even be built into the lockshield valves at the ends of the radiators. If there's more than one 'low point' (eg if the ground floor's solid and each if your downstairs radiators is fed from a 'loops' of pipe dropped down from the first floor, then each such 'loop' should have a drain point. That being said, it's unfortunately very commonplace for these to be left off the system altogether by the cheapskate/idle heating engineer who installed the system, so don't be too surprised if you can't find it/them! If you can't, then you basically have to gradually undo a coupling at a radiator valve, and collect the water which comes out - takes a long time and may well be messy. Do you really need to do it? And then you fit a drain cock before refilling....! I certainly can't see how plumbers can have actually drained the system before from your description - what task were they doing at the time? David No I don't really need to do it but I'd like to give it a flush and put in inhibitor. Plumbers were in fixing leaky radiators both upstairs and downstairs I think and I'm 99.9% positive they drained from inside boiler(should've asked them when they were in). I can get under the floor but they definitely didn't go under there to drain it down. Boiler is on wall in kitchen at height of wall cupboards in the floor cupboard beneath boiler I have the filling loop. I've took front cover off boiler and can't see anything that looks like screwfix picture link. I'm doing up kitchen at the moment and will be replacing old rad which I'll be able to manage. So I was intending putting in fernox flush while fitting new rad but then I've still got the problem that this will need drained and then flushed a couple of times before adding inhibitor. Cheers Why the heck don't systems have a proper drain - to the outside of the house. |
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