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https://www.askthetrades.co.uk/cgi-bin/yabb/YaBB.pl DIY Forum >> Plumbing Questions >> C/H Project https://www.askthetrades.co.uk/cgi-bin/yabb/YaBB.pl?num=1081528397 Message started by squiggle on Apr 9^th, 2004, 5:33pm

Title: C/H Project
Post by squiggle on Apr 9^th, 2004, 5:33pm

Hi, I'm hoping you can save me a few hrs of research. When my mother moved into her bungalow about 5 years ago, she had a plumber fit a new boiler, etc. but its been a problem system ever since. I'm toying with the idea of trying to make a few changes. I'll try to describe the system as it is before asking several questions...

It is a fully pumped open vented system. There is a time switch/programmer for C/H and H/W and one normaly closed motorised valve on the C/H side of the circuit. There are no other controls.

The problems we have are:

1: It always seems to need bleeding.
2: With just H/W on, radiators can get warm, I guess some sort of backflow problem?
3: In the winter, we often end up with a situation where the H/W is scalding hot and the radiators may still not be very warm - the only temperature control is the boiler stat.

My thought for problem #3 is to try to convert the system to what looks to be a Honewell S Plan, ie. add a motorised valve on the H/W side, add a room thermostat and a cylinder thermostat.

Question time:

1: Would that solution make sense and/or are there better ones?
2: If I was to fit the second valve, I'd need to cut a pipe in the roof - how does one empty and fill the system?
3: In my reading so far, I see there are programmable room stats. C/H tends to get switched on constant and forgotten about. Are these things any good and worth the extra investment?
4: Any suggestions to problems #1 and #2?

Thanks for any help,

Jon

Title: Re: C/H Project
Post by Mike_Jackson on Apr 9^th, 2004, 5:52pm

It sounds like a bit of a bodge from the start.

Was it converted from a gravity hot water system?

I would suggest that you get a professional round to have a look as fitting extra valves could block the path to the open vent or cold feed and compromise safety.

Mike

P.S. The energy saving trust recommends programmable room thermostats and thermostatic radiator valves.

P.P.S. If your mother is elderly she may qualify for grants to upgrade the heating. Regardless of this any control upgrades carried out by a professional are only liable to VAT at 5%

Title: Re: C/H Project
Post by HandyMac on Apr 9^th, 2004, 5:58pm

I agree with Mike about getting a pro to take a look. In fact if his quote for sorting isn't reasonable then get maybe 3 different quotes before making a commitment. If you get 3 different experts telling you much the same thing then you can be fairly sure where the problems lie.

With respect to having to continually bleed the system one possible issue might be that the system was never filled with inhibitor. I dunno what inhibitor includes, but I've always thought that these prevent the water in the system breaking down into gas constituents (which is what you bleed off when you open a bleed valve).

Please note - I do not profess to be an expert with CH systems. I've installed a CH system and know my way around them from a general laymans point of view, but the best advice will come from someone who is a professional CH installer. I reserve the right to be overridden by their expert views :)

Andrew

Title: Re: C/H Project
Post by Plumber on Apr 9^th, 2004, 6:25pm

It sounds to me that it has been poorly installed from day one

point 1 probably due to incorrect pipe configoration, causing air to be drawn into the system

point 2 again incorrect pipe configoration causing reverse circulation

point 3 probably due to no valve on HW primaries, hot water is taking priority

You definately need a two port valve on the hot water you cannot control the hot water without one
you would be wise to call in a qualified engineer to survey the system and give his oppinion and remedy suggestion, get at least three different quotes and use reputable engineers try the Institute of Plumbing www.plumbers.org.uk you can then use the search facility to locate local engineers

Title: Re: C/H Project
Post by squiggle on Apr 9^th, 2004, 6:37pm

Thanks for the advice. As Mike seems to have guessed, money is a bit of a factor here and my mother is retired. If a grant is available, I'm pretty sure that will be the route we take.

>It sounds like a bit of a bodge from the start.

Was it converted from a gravity hot water system?<

I don't know if it was gravity or not but I doubt it. The H/W cylinder is only just above the height of the top of the floor standing boiler and I believe the previous boiler was wall mounted.

Bodge from the start, yes! I don't know the full history but I believe that the original system was a DIY job and also, I don't know at what point, an extension was added to the building providing a new living room. When my mother bought the house, she decided to use what would have been the original living room which is the other side of the kitchen to the rest of the building as a "guest bedroom" but the boiler was there (and apparently horribly smelly with oil). The plumber fitted a nice new boiler in the kitchen but as you see from my first post, some problems remain.

Jon

Title: Re: C/H Project
Post by Mud on Apr 9^th, 2004, 7:40pm

Though I strongly advise you not to, if however, you do decide to do some work on this system, adding a 2nd motorised valve to the hot water circuit could compromise the safety of your heating system. You will require an automatic bypass directly after the pump to prevent the flow from your boiler being shut off completely.

Title: Re: C/H Project
Post by thescruff on Apr 9^th, 2004, 10:56pm

As I say on other forums, the safest plan is to email me a drawing as is, and I can modify where required.

That way theres no guessing what goes where etc.

scruff

Title: Re: C/H Project
Post by squiggle on Apr 10^th, 2004, 10:36am

Thanks for the offer scruff. but:

a) I'm not sure where to begin with drawing a plan and
b) Having read the comments here, it does seem to me that there is likely to be a lot more wrong with the system than I realised and that things could be tricky...

I'm going down the route of investigating the possibility of grants and getting estimates from professionals first. From then on, it will all depend on cost. The last job on the system (which did include a boiler, new plastic oil tank, programmer, one zone valve and thermostatic rad valves) came to over �2K - we don't want to and can't afford to lay a lot more out on the system.

Jon

Title: Re: C/H Project
Post by thescruff on Apr 10^th, 2004, 11:13am

Thats the idea of having a drawing , without it we can only guess.

A simple line drawing in word or use a scanner if you have one, to show the main bits.

scruff

Title: Re: C/H Project
Post by squiggle on Apr 10^th, 2004, 5:39pm

OK scruff, as I said I think we will look to pro routes at least first but I guess there is no harm in demonstrating to the world that I can't draw diagrams to save my life...

I'm not clear how this forum works for links but I will try HTML...

The best I can come up with for a plan is at http://www.folkinfo.org/temp/plumb1.jpg

I've also put a picture of one bit where the valve is at http://www.folkinfo.org/temp/plumb2.jpg

If nothing else, it would be interesting to see if a plumber can make any sense of my attempt.

Jon
--
Edited as I think I now see how links work and had missed the preview button.

Title: Re: C/H Project
Post by Mike_Jackson on Apr 12^th, 2004, 9:35am

If I'm looking at your diagram correctly the pump is on the return. When the zone valve to the heating shuts the extr pressure could well lead to pumping over which puts more air into the system leading to frequent venting.

This ingress of air leads to corrosion and a build up of magnetite sludge etc. If this moves around the system it can prevent the zone valve from closing completely.

My recommendations for your Mothers system would be

1. Move pump to the flow and convert to a close couple feed and vent.

2. Fit another zone valve and auto bypass to convert to S Plan.

3. Fit a cylinder stat, programmer and programmable room stat.

4. Fit TRVs to all rooms bar the one containing the room stat.

5. Upgrade the insulation to all pipework within the roof space.

6. Fit at least one auto air vent at high level to the system.

7. Powerflush the system to remove all of the ccumulated debris.

It is worth looking at the state of the other zone valve and possibly replacing that or conerting to a Y plan.

I wouldalso suggest this is probably beyond your average DIYer.

If I've missed anything I'm sure someone will remind me.

Mike

Title: Re: C/H Project
Post by thescruff on Apr 12^th, 2004, 9:49am

Spot on Mike.

The pump is on the boiler return.

The alterations I suggested are identical to yours, and should be very easy to change.

The pump can be moved to the loft space with the cold feed/vent all in the flow.

A second MV is added for the hot water primary.

An auto bypass is needed.

And the return you may have noticed thats connected wrong, can be reconnected in the heating return.

I can post you an as suggested drawing if you send your email, not into computors enough to be ably to linkit.

Title: Re: C/H Project
Post by squiggle on Apr 12^th, 2004, 10:44am

Thanks again for comments/suggestions.

The situation with TRVs at the moment is that every radiator is fitted with one. I did read somewhere (which seems to tie in line with MJ's comments) that this should not be.

Title: Re: C/H Project
Post by thescruff on Apr 12^th, 2004, 1:03pm

Jon,

You could post the last drawing on your link, for the benifit of others. (005 I think)

will take you up on the pint if I knew where it was :-[

scruff

Title: Re: C/H Project
Post by squiggle on Apr 12^th, 2004, 1:48pm

OK Scruff, I've put your word doc at http://www.folkinfo.org/temp/jf-005.doc

I can try to produce a pdf version should anyone interested not be able to read a MS Word document.

It's North Norfolk BTW.

Jon