Advanced search

Advice please- I have a very old central heating system with no thermostat. Replace?

(29 Posts)
shoom Thu 20-Mar-14 07:15:32

I have recently bought a house with a 20 year old gch system. It is the type with a boiler and separate hot water tank. The only controls are a mechanical timer clock on the hot water tank and thermostats on the radiators. It seems to be working ok although some radiators have cold spots (they don't need bled, it's possibly sludge or insufficient water pressure?). Do I replace the system ahead f it failing? With what?

My heating engineer said it's possible to add a digital control to the tank to give different room temperatures at different times of day (and presumably control the temp of the hot water). He also said the boiler itself essentially can't be repaired if it fails as the manufacturer has priced replacement parts very high to encourage people to replace the whole boiler. However the boiler is a simple mechanism that could run happily.

So I'm wondering if I should replace the system ahead of it eventually failing (with what?) Also does this mean I can lose the cold water tank. in the loft?

I have been used to combi boilers in flats so this is all new stuff. My heating engineer is not at all had sell although he does fit new systems, sso I think he's not pushing a sale although he would replace the system if it were his own house.

shoom Thu 20-Mar-14 07:19:10

It's a "glow worm" boiler and "boiler mate" hot water tank.

WhatWillSantaBring Thu 20-Mar-14 07:56:26

Similar position but with an oil fired boiler (no mains gas). My research suggested keeping the old boiler as, although inefficient, it's simple and can keep going for years. I was told that new boilers have about a 10year life so only just pay for themselves in efficiency savings. How true this is, I don't know, but we've chosen to spend the new boiler budget on fun stuff (like an aga!)

wonkylegs Thu 20-Mar-14 08:15:02

We've just replaced a 25yo glowworm boiler & old tank.
We replaced with a new Worcester conventional condensing boiler (rather than a combi condensing boiler) and a megaflo tank. We went down the conventional route because it copes better with the masses of rads & multiple bathrooms, the megaflo gives us good pressure HW like a combi.
We also replaced the basic controls with a Honeywell 7day programmer & TRVs. When we did the work we had everything flushed to get rid of 25yrs of accumulated crud.
The difference between the old system & the new one is massive & was well worth it for our house.
We are planning on staying for 20yrs though so it seemed a very valid investment.
It may be worth considering different options that work with your house - there is good advice on the Worcester Bosch website even if you don't buy one of theirs.

hiccupgirl Thu 20-Mar-14 08:36:07

We replaced a 30 yr back boiler, hot water tank, no central thermostat system with a combi boiler, house thermostat and new radiators in our house. It was a big job cos the gas supply had to be moved to the other side of the house but well worth it.

Our back boiler was still going strong but no-one would service it and it was totally non compliant with all the modern safety standards. It was also eating gas in comparison to the new system.

I would say its worth replacing the system even if you're not going to stay there forever. A new boiler etc is attractive to buyers plus you get the benefit of cheaper and more reliable heating.

shoom Thu 20-Mar-14 08:48:02

Thanks for your comments they are really useful. It's a 3 bed semi and hopefully my home for the foreseeable future.

Indith Thu 20-Mar-14 08:54:50

depends on how much you want to spend I guess. As your engineer said you can just fit a thermostat. But am old boiler won't be very efficient so even with a thermostat will cost more to run in the long run. Have you looked into grants? You may well be able to get something towards replacing it, there are various grants available to replace old boilers with energy efficient ones.

MooncupGoddess Thu 20-Mar-14 08:58:51

Are you basically happy with how it works? If so, I'd leave it for now. I have a similar Glowworm (but combi) and not a thermostat in the house, but it does me just fine, so I can't see the need of replacing for the sake of it. At some point it will start misbehaving and you can make a plan then.

PigletJohn Thu 20-Mar-14 09:29:49

Well for heavens sake start by fitting a thermostat. Get a wired one because they are simpler and more reliable than wireless.

Unless you have a very simple daily schedule, get a programmable stat because it enables you to set times and temperatures to suit you, which can vary by time of day an time of week. Honeywell currently leads the market. Look at a CM907. Or a simple stat is very very cheap.

Have a look at your insulation as well. The previous homeowner with no room stat obviously had no idea of how to manage heating for comfort and economy.

If you have cold patches on your radiators, your next job would be to consider a simple chemical clean combined with fitting a system filter. This will be much cheaper than a power flush and is likely to make a big improvement. Do your radiators have microbore pipes (10mm diameter) or 15mm?

PigletJohn Thu 20-Mar-14 09:38:19


Your Gledhill boilermate will be providing hot water at mains pressure, and is quite advanced for its age, so if in good condition is worth hanging on to. It is quite likely that there is not a large cold water tank in the loft. I suppose it has a white case?

Madmog Thu 20-Mar-14 09:58:52

Our boiler couldn't be repaired and parts had become obsolete, so we were without heating for six weeks in the winter. We just about managed, but having showers in a cold room (10c) was no fun, and our daughter had to cope with it as well. If this doesn't bother you, you could keep your present one going for however long it lasts, but if you want to prevent this then spring/summer would be a good time to have a new system installed.

specialsubject Thu 20-Mar-14 10:06:36

condensing boilers are indeed supposed to be less reliable but there's almost no choice on that. Do you know how efficient the current boiler is compared to a new one?

I would also suggest a chemical flush of the system - there are ones that are gentle on old systems. Powerflushing is a waste of time if you do have microbore.

your problem is of course that if it does fail, you'll need a replacement in a hurry. And if that failure is in winter you'll be waiting ages for a gasman. In summer they are kicking around.

oil boiler person; we replaced our 30 year old noisy one that came with the house with a new one. The reduction in oil consumption is already massively noticeable and I reckon it will pay for itself in about four years -and that is assuming that prices don't go up. (yeah, right..)

PigletJohn Thu 20-Mar-14 10:24:37

New boilers are all condensing, with a few very rare exceptions that you may be permitted to use e.g. in a listed building.

However combis are more complicated than regular boilers, have more to go wrong, and are more inconvenient when they do. I am not a combi fan so I know I will sound biased. People in single- occupancy homes are often happy with them.

Beware of people saying "my modern, efficient combi is cheaper to run than my 30-year old, cast iron conventional boiler was." The modern-ness and the efficiency are the reason, not the combi-ness.

specialsubject Thu 20-Mar-14 10:56:04

I should probably clarify that my new boiler is NOT a combi. Deliberately avoided that. Hate the things - but then I do have space for a hot water tank.

PigletJohn Thu 20-Mar-14 10:57:56

Very wise (wink)

MooncupGoddess Thu 20-Mar-14 11:25:57

"The previous homeowner with no room stat obviously had no idea of how to manage heating for comfort and economy."

Ha, that must be me. I did look into getting all of that set up but for someone in my position (single, out most evenings, very low gas bill) it just didn't make sense. My flat is very comfortable with the heating on the timer for an hour in the mornings and evenings during the cold weather, plus an extra hour or so at other times if I feel chilly.

Of course the OP's lifestyle and needs are probably entirely different, but my point was that she should start from a position of assessing her current situation and whether she's happy with it or not. It's always tempting to spend lots of money on new kit which then takes a very long time to pay for itself.

PigletJohn Thu 20-Mar-14 11:58:00

cheapest (but it works)


shoom Thu 20-Mar-14 13:14:18

Thanks again everyone.

PigletJohn I don't know the size of the radiator pipes offhand and will check that. When you talk about insulation do you mean the boiler mate? There's no jacket on it. Thanks for the link to the room thermostat. Can I order that and ask an electrician or heating engineer to fit it, or do I need to check if it is compatible with my boiler mate?

I haven't moved in yet but the system seems to provide heating and hot water reasonably well, excepting the one or two cold radiators. The others are piping hot. So maybe a room thermostat and a chemical flush may be a good option? I can't imagine the previous owners tied one, they seemed to just ignore maintenance tasks and cover up problems.

PigletJohn Thu 20-Mar-14 13:22:23

if the boilermate has a white metal casing, it probably has good insulation inside that, but over the water vessel inside. However hot pipes, especially between the boiler and the boilermate, will benefit from good insulation, Climaflex or similar. They are probably 22mm, which is widely available, or 28mm, which is not. There is a "water regulations" grade which is as thick as your arm, or an economy grade which is not as good but may be easier to fit if the pipes are tight to a wall. You cut and trim it with a breadknife.

Post a pic if you can, I've never seen an old one. There may be a plate or label on it with model number or date of manufacture.

If you have some hot and some cold radiators, turn off the hot ones and see if the cold ones heat up.

TRVs do not last forever, post photos or descriptions please. With a boilermate it was probably a good-quality installation when new.

PigletJohn Thu 20-Mar-14 13:32:13


An electrician or a heating engineer can fit a room stat, it will be wired into the timer, possibly using a new connection box. Easy job. Have a think about where you want the wire to be run. If chased into the wall it will need redecorating afterwards, but it could also be run along the skirting or drilled through the wall into an adjoining room. The stat is best positioned in the living room that you use most often, and always heat, but away from cookers, radiators or fires. It should be at about the same height as a light switch. Ask the person who is fitting it if he can get it for you at an inclusive price and cover it with his guarantee, he may prefer that. Honeywell are best but ACL Drayton and Danfoss are also good. There are a few budget brands that a good heating engineer will avoid. Salus is a very cheap brand in many ways.

A heating engineer or plumber can do the chemical clean and fit filter. It is not gas work so does not need a qualified gasman. Experienced plumbers will know how. Or it is a DIY job if you like plumbing.

The boilermate includes its own thermostatic control for the hot water, I don't think you can adjust the temperature of the tapwater except with a mixer tap.

PigletJohn Thu 20-Mar-14 13:40:57

out of interest

they do offer fixed-price servicing and maintenance contracts if you can't find anyone local. I don't know if it is a good deal or not, they are fairly simple. I'd be inclined to keep it unless it becomes uneconomic to repair. It should be better than a combi for a bath or shower.

shoom Sat 22-Mar-14 12:53:58

PigletJohn thanks again, here are the photos.

The radiator pipe seems to be 10mm diameter.

My heating engineer suggests the wireless version of the honeywell thermostat, CM927, or the wired version that you suggested.

shoom Sat 22-Mar-14 12:56:03

The photos look blurry now. The boiler mate II has a metal coloured tank. The radiator controls are likely original, 20 year old ones.

PigletJohn Sat 22-Mar-14 13:34:00

oh, it appears to be silver, hammer-finish paint, and round not square. I was not expecting controls to be on the front of it.

Would be worth emailing Gledhill to ask for the instructions, they probably have them online. Ask what insulation it has.

When you have tried the "turn off the hot ones" trick, if the hot ones don't go cold when turned off, or the cold ones don't then warm up, you may have some failed TRVs. The best brands you can still get replacement parts for, even at that age, and you can swap the thermostatic heads (plastic part), but I don't recognise those TRVs. See if there is a makers name on the top of any of the knobs.

If you turn the knobs down to number 1 or 2, you should find the rooms keep at quite a cool temperature, and the rads get hot, then each rad will cool off once its room has reached (say) 15C target temperature. It takes an hour or more to see if they are working. The valve in your photo appears to have PTFE tape (white, very thin plastic) on its connector threads, suggesting the radiator has recently been removed, e.g. to stop it leaking or to fit a new one, or possibly during redecoration. You can pull off the loose scraps of tape if you want.

If the pipes are 10mm microbore, it makes alterations more tiresome. However you do not seem to have both pipes on the same end of the rad, which is good. Measure them again to make sure (cut a 10mm notch and a 15mm notch in a piece of card, and push the notches over the pipe to see which fits)

PigletJohn Sat 22-Mar-14 13:41:25


I'd suggest you get prepared, then have the plumbing work done once the weather warms up. The engineer will be less busy, and less likely to be called away to an emergency, and might possibly have better prices when trade is slack; and if it's warm, you won't mind the heating being off.

The room stat however you can fit at any time without the heating being out of order for more than an hour or so, and it will immediately start saving you money.

Join the discussion

Registering is free, easy, and means you can join in the discussion, watch threads, get discounts, win prizes and lots more.

Register now »

Already registered? Log in with: